7. is (4x+9)/7=f(x) because you switch the x and y and then solve for y.
f(x)=y
y=(7x-9)/4
x=(7y-9)/4
4x=7y-9
4x+9=7y
(4x+9)/7=y
-(-5)+7-18+4 first yo distribute the negative so it would be 5+7-18+4=-2
Divide 105 by 7 to get 15
You can use Google or a calculated but to check it but it's : 6
