To solve a word problem with an unknown quantity, treat the unknown quantity as a variable.  The best equation for the problem above is:  

then solve:

To solve a word problem with an unknown quantity, treat the unknown quantity as a variable.  The best equation for the problem above is:  

then solve

To solve a word problem with an unknown quantity, treat the unknown quantity as a variable.  The best equation for the problem above is:

use algebra to solve

To solve a word problem with an unknown quantity, treat the unknown quantity as a variable.  The best equation for the problem above is:  

use algebra to solve

In this problem we have one unknown, Jon's age. 

We must list what we do know:

Vicki is 21 years old.

Jon is twice Vicki's age plus 5 years

If we let J=Jon's age we could setup an easy equation:

so Jon is twice Vicki's age, 21, plus 5 more years. If we solve the equation we find out that Jon is 47 years old:

We can solve this problem by setting up a simple equation.  We do not know the amount we paid, so we will assign that a variable, x.  So, 

We know that if we subtract the total from the amount we pay, we will get the amount of change.  So, we will solve for x.  We must add $24.63 to both sides.  We get

Therefore, we gave the cashier $35.

Michael makes  more than twice Eli. 

If Eli makes  then double that and add  and that would be Michael's amount.

Eli makes  free throws.

In this problem there is one unknown and in this case it is how much Jacob spent on his brother's birthday gift. 

Let x=the amount of money spent on his birthday gift. We know that he spent $30 more on the birthday cake than on his brother's gift, so  because he spent $60 on the birthday cake.

Solving for the equation we have:

When you do not know the value of something, you assign it a variable.  In this case, we do not know how much a bottle of water costs, so we will assign it a variable.  We know we bought 9 bottles.  We also know that our total cost is $11.25.  So, we can set up the equation.  We get

where x is the cost of a bottle of water.  Now, we solve for x.  We must divide both sides by 9.  We get

Therefore, a bottle of water costs $1.25.

The first step is to figure out the perimeter of the square play yard with an area of 225 meters, first using the fomula: 



Find the square root of both sides to calculate the length of the base of the square



All the sides are of equivilent length, so the total amount of fence required is:



One side is "fenced" by the house, so that fenching does not need to be paid for. Thus, only the remaining 3 sides need to be paid for.

Finally, multiply the length of fencing needs by the cost of fence per foot to find your answer: