It is the second one 2a +b over 4
T.S.A. = pi (7) (24) + pi (7)^2 = 168pi + 49pi = 217 pi cm^2 = more or less 681,73 cm^2
X = rate of mechanic who worked 5 hours
y = rate of mechanic who worked 15 hours
x + y = 200
5x + 15y = 1950
you find the first variable in one of the equations, then subsitute the result into the other equation. your answer would be:
the mechanic who worked for 5 hours charged $105 per hour, the one who worked 15 hours charged $95 per hour.
hope this helps :)
