Xavier can paint the average house in 4 hours, while Mohamad can do it in 12 hours. Find the number of hours, $$, that it would take to paint a house if they both worked together.

3 hours

Step-by-step explanation:

Xavier can paint the average house in 4 hours

This means that in 1 hour, Xavier paints 1/4 of the house

Mohamad can do it in 12 hours

That means in 1 hour, Mohamad paints 1/12 of the house

Hence,

Together the amount of the house they can paint in 1 hour is

1/4 + 1/12

The Least common denominator is 12

(3 × 1 + 1 × 1)/1#

= 3 + 1/12

= 4/12

= 1/3

Together they can paint 1/3 of the house

The number of hours, that it would take to paint a house if they both worked together is

= 1/3 = 1

Cross Multiply

= 3 × 1

= 3 hours

f(x) has value 150 at x= 0

and 0 at x= 3

so d(f(x))/dt = slope = -150/3 = -50