ACT Math : How to evaluate algebraic expressions

Study concepts, example questions & explanations for ACT Math

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Example Questions

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Example Question #31 : Evaluating Expressions

If  is defined by the formula , what is  equivalent to?

Possible Answers:

Correct answer:

Explanation:

The function  is defined by . This means that for whatever value is in the space of the  before the symbol , in our case 2, is inserted into any  in the defined function:

For the value that follows , the  value of 1 in our case, is inserted into any  variable in the defined function.

Then simplify:

 is our correct answer after all the simplification.

Example Question #67 : Expressions

A dress that normally costs $80 before tax is on sale for 15% off. After the discount is subtracted, a 7% sale tax is added. What is the final price of the dress?

Possible Answers:

Need more information

Correct answer:

Explanation:

The word problem can be simplified into two steps. First, subtracting the 15% discount:

Second, adding the sales tax to the result from the first step:

The percentage is represented as a decimal by dividing the percentage by 100.

So, for the numbers provided:

New Price = 

Final Price = 

 

Example Question #68 : Expressions

Evaluate the expression: 

 

for  and 

Possible Answers:

Correct answer:

Explanation:

Plug in the values for the variables and use PEMDAS to dictate the order of the operations. PEMDAS stands for Parentheses, Exponents, Multiplication, Division, Addition, and Subtraction. Using this order of operations we get

  so the first part of the expression is .

Next we deal with the exponents,

.

Then, we deal with the multiplication, 

 

Finally, we plug these simplified values back into the equation and solve,

.

Example Question #69 : Expressions

Tickets for a circus show cost  each when bought in advance and  each when bought at the door. The circus show's goal is to acquire at least  in ticket sales. The show group sold  opening-night tickets in advance.

What is the minimum number of tickets they need to sell at the door on opening night to reach their goal?

Possible Answers:

Correct answer:

Explanation:

Since  tickets were sold in advance, the group earned a revenue of . In order to reach their goal of , they would still need to earn an extra

Since each ticket costs  at the door, the theatre would need to sell tickets, or  tickets (rounded to the next whole number).

Note: the answer is NOT  tickets, because if  tickets are sold, the revenue would be  , which does not reach the goal of .

Example Question #70 : Expressions

If , what is the value of ?

Possible Answers:

Correct answer:

Explanation:

Since  this value can be substituted for  in the function.

Here, the denominator becomes , while the numerator becomes .

Hence, 

.

Example Question #31 : How To Evaluate Algebraic Expressions

If  , then  equals?

Possible Answers:

Correct answer:

Explanation:

When substituting  for  in the provided equation, we get

,

which can be simplified to

, or .

Example Question #971 : Algebra

Question 20

In which month has Abraham collected the most stamps?

Possible Answers:

October

July

November

May

April

Correct answer:

May

Explanation:

May corresponds to the month Abraham collected the most stamps, adding 24 to his collection. April, July, October, and November correspond to 18, 6, 21, 12, respectively.

Example Question #33 : How To Evaluate Algebraic Expressions

A company establishes a rewards program such that the bonus received by an employee is given by the model , where  is the number of sales an employee completed. If Alex earned $2700 at the end of the month, how many sales has he completed?

Possible Answers:

Correct answer:

Explanation:

Alex’s bonus of 

Example Question #31 : Evaluating Expressions

 , then 

Possible Answers:

Correct answer:

Explanation:

 . Thus

 

Example Question #32 : Evaluating Expressions

Evaluate the folling expression given .

Possible Answers:

Correct answer:

Explanation:

To evaluate, simply plug in  for . Thus:

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