Question 140719
the number of children (n) is a function of the fee (f), so n=mf+b


the slope (m) is the change in n (+10) divided by the change in f (-20), so m=10/(-20) or -1/2


to find b, use the given point (100 children, $250 fee)
__ substituting __ 100=(-1/2)(250)+b __ 100=-125+b __ 225=b


so the equation is n=(-1/2)f+225


f is the independent variable, graphed on the horizontal (x) axis


n is the dependent variable (depends on f), graphed on the vertical (y) axis


for a $180 fee __ n=(-1/2)180+225 __ n=-90+225 __ n=135