Beth needs 5 1/4 quarts of paint to paint some walls. how much will it cost her? (assume she can buy a fraction of a quart at the same rate.)

If a quarter of a gallon of paint costs 13.99 $:

This means that a full gallon costs in dollars  

gallons of paint is needed.

Then the total cost in $ is:

If a full paint gallon costs $ 13.99:

This means that a quart of paint costs in dollars

gallons of paint is needed.

Then the total cost in $ is:

set each factor equal to 0

4x-3 = 0

2x-1 = 0

solve for x.

4x-3=0

4x=3

x= 3/4

solve for x. 

2x-1= 0

2x= 1

x= 1/2

eventually after a few more steps, your answer should be 1/2 is less than or equal to x and 3/4 is greater than or equal to x