42 should be the right andwer
The answer would be a 3x-4y=-10
The formula for volume of a sphere is 4/3pi(radius)^3
So 4/3(3.14 - better to use the pi button on your calculator)(4 cubed)
Punch into calculator (And I mean PUNCH that thing)
Volume = 268.08 in.^3. Divide this by 2.5 = 107.23 seconds.
It is proportional because the relationship between gallons of gas and distance is constant and linear. The rate is 32 miles per gallon. You can also call 32 the slope of this linear relationship.