I'm pretty sure its the 3rd one
Answer:
sweatshirts cost $42
t-shirts cost $18
Step-by-step explanation:
9x+3y=288
x+6y=270
substitute 270-6y for x in the first problem
9(270-6y) +3y=288
2430-54y+3y=288
2430-51y=288
51y=-2142
y=42
then plug y=42 into the second equation
x+6(42)=270
x+252=270
x=18
Product difference would be it
T = 5, so after 5 years
p(t) = t^3 - 14t^2 + 20t + 120
Take derivative to find minimum:
p’(t) = 3t^2 - 28t + 10
Factor to solve for t:
p’(t) = (3t - 2)(t - 5)
0 = (3t - 2)(t - 5)
0 = 3t - 2
2 = 3t
2/3 = t
Plug 2/3 into original equation, this is a maximum. We want the minimum:
0 = t - 5
5 = t
Plug back into original:
5^3 - 14(5)^2 + 20(5) + 120
125 - 14(25) + 100 + 120
125 - 350 + 220
- 225 + 220
p(5) = -5
