Answer:

Step-by-step explanation:

pull 2 from top

we are looking to cancel (x-5) so will start with
(x - 5)(x + 3), selected (x+3) because the sign must be negative and must multiply to -15
now cancel (x-5)

Maria do 1/2 work in 1 hour
Sasha do 1/3 work in 1 hour
Thus,
1/2+1/3=5/6 work in 1 hour
5/6 work in = 1 hour
1 work in =6/5=1.2 hours =72 minutes
F(x) = 112 - kx
f(-3) = 121
f(-3) = 112 - k(-3)
f(-3) = 112 + 3k
121 = 112 + 3k
121 - 112 = 3k
9 = 3k
9/3 = k
3 = k <===