Look this american “ñ” hahaha
Answer:
C. Exponential decay
Step-by-step explanation:
Answer:
12 hours
Step-by-step explanation:
Let Theo's siste can paint a fence in x times
Given.
Theo can paint a fence three times as fast as his sister can. Working together, they can paint a fence in 9 hours.

Apply cross multiplication

Theo’s sister to paint the fence in 12 hours.
Xy=12
xdy/dx + y = 12
xdy/dx = 12 - y
dy/dx= (12-y) /x
dy/dx | x=-4 ,y=-3 = (12-(-3))/(-4)
= (12+3)/-4 = -15/4