Let's make an equation where x is the number of gallons and y will be the overall price.
2.5x=y; since it is $2.52 PER gallon, you need to multiply the amount of gallons by the cost. In this case, it is 4.
2.5(4)=10
So, the price of 4 gallons is $10.
Assuming you are focusing on the square only, then the answer is 9 inches.
You take the square root of 81 to get 9. Notice how 9^2 = 9*9 = 81. So if you're not familiar with square roots, then think backwards in a sense to get the answer.
The slope is 3 and y-intercept is 4
y=mx+b
= 30%
= 0.3
= 3/10
Hope this helps.
