If Ann can build the model in 3 hours, then in 1 hour she gets 1/3 of it done. Likewise, if Sam can build the model in 6 hours, then in 1 hour he gets 1/6 of it done. We are looking to find how long it takes when they combine their efforts, so we will add the two together and set it equal to 1/x, x being the number of hours it takes for both of them to get the whole job done. The equation then looks like this:
. You will have to find the common denominator to add those fractions, and once you do, cross multiply to solve for x.
Answer:

Step-by-step explanation:

Isolate d

.
Divide both sides of the equation by b

Simplify

Answer:
( x - 6 ) ( x - 3 ) (x + 4)
Step-by-step explanation:
Since it is a slope, the equation of a slope is y=Mx+b. So you want to get b to that format. To do this, you need to isolate the y on the left. To do this, you simply add 2x to both sides. Your final answer will be y=2x+7. Hope this helps!