All ACT Math Resources
Example Questions
Example Question #311 : Algebra
3x + 9i2 – 5x = 17
What is x?
–1
–13
4
13
–4
–13
i =
i2 = -1
3x + 9i2 – 5x = 17
3x + 9(–1) – 5x = 17
–2x – 9 = 17
–2x = 26
x = –13
Example Question #312 : Algebra
Solve for x:
3x + 4y = 26
–5x + 12y = 14
Eliminate y and solve for x.
3x + 4y = 26 (multiply by –3)
–5x + 12y = 14
(–3)3x +(–3) 4y = (–3)26
–5x + 12y = 14
–9x +-12y = –78
–5x + 12y = 14
–14x + 0y = –64
x = –64/–14 = 32/7
Example Question #313 : Algebra
Michael is counting his money. He notices he has one more quarter than he does dimes, as well as one less nickel than dimes. The total cash he has is $2.60. How many coins does he have in total?
The general form for money problems is , where is the value of the coin and is the number of coins.
Let = # of dimes, = # of quarters, and = # of nickels.
So, , and solving gives . Therefore there are 6 dimes, 7 quarters, and 5 nickels, giving 18 coins in total.
Example Question #1804 : Act Math
What value of will satisfy the equation
The answer is .
The solve this equation, first distribute the to obtain
Proceed to subtract from both sides to get
Subtract from both sides to leave
Divide both sides by to get the answer,
Example Question #34 : Equations / Inequalities
Given that , what is the value of ?
First, we must solve the equation for by subtracting from both sides:
Then we must add to both sides:
Example Question #35 : How To Find The Solution To An Equation
Internet service costs $0.50 per minute for the first ten minutes and is $0.20 a minute thereafter. What is the equation that represents the cost of internet in dollars when time is greater than 10 minutes?
The first ten minutes will cost $5. From there we need to apply a $0.20 per-minute charge for every minute after ten. This gives
.
Example Question #31 : How To Find The Solution To An Equation
John goes on a trip of kilometers at a speed of kilometers an hour. How long did the trip take?
If we take the units and look at division, will yield hours as a unit. Therefore the answer is .
Example Question #33 : How To Find The Solution To An Equation
With a head wind a plane can fly a certain distance in five hours. The return flight takes an hour less. How fast was the plane flying?
In general, .
The distance is the same going and coming; however, the head wind affects the rate. The equation thus becomes .
Solving for gives .
Example Question #34 : How To Find The Solution To An Equation
How much water should be added to of 90% cleaning solution to yield 50% cleaning solution?
Pure water is 0% and pure solution 100%. Let = water to be added.
in general where is the volume and is the percent.
So the equation to solve becomes
and
Example Question #35 : How To Find The Solution To An Equation
Solve and
This problem is a good example of the substitution method of solving a system of equations. We start by rewritting the first equation in terms of to get and then substutite the into the second equation to get
.
Solving this equation gives and substituting this value into one of the original equations gives , thus the correct answer is .
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