How do i find the equation? (with explanation ? )

First find the slope of the equation you are given

5x-4y=10
-4y=-5x+10
y=5/4x+10

So your slope is 5/4

Parallel lines have the same slope so the slope of line q is 5/4

Now use the point-slope formula to find the equation

y-(-7)=5/4(x-12)
y+7=5/4x-60/4
y+7=5/4x-15
y=5/4x-8

Line q’s equation is y=5/4x-8

B. 2 1/2 feet. multiply 2.5 inches by 12 to get thirty inches then divide by 12 to get 2.5 feet