Answer :
f(s) = 10(s - 65) + 75
f(s) = 10(s) - 10(65) + 75
f(s) = 10s - 650 + 75
f(s) = 10s - 575
f(s) = 10(s) - 10(65) + 75
f(s) = 10s - 650 + 75
f(s) = 10s - 575