(s(t+h)-s(t))/(h)=(1-10(t+h)-(1-10t ))/(h) URGENT

Grandma made an apple pie. josh and his brother joe finished 4/5 of it. then 3 friends came over and shared the left over. how much pie did each friend eat

Can someone me with this problem . show your work .

If g^-1(x) is the inverse of g (x) which statement must be true