Answer:
On average, the slide drops 14 feet for every 3 feet of horizontal distance.
On average, the slide drops about 4.7 feet for every 1 foot of horizontal distance.
You want to isolate the variable 'y'.

Subtract 10 to both sides:

Divide -3 to both sides:
I think you're supposed to substitute -5 into x. So now the equation is
f(-5)= 6(-5) +7.
f(-5)= -30+7
f(-5)= -23
As a result, the value of f(-5) is -23