This is really a easy question just plug what they give you in
Answer:
Multiply both sides by 
Step-by-step explanation:
Given

Required
Get an equivalent of 
To do this, we simply multiply through by 








Answer:
1. Formula: b * h ÷ 2
12 * 3 = 36 ÷ 2 = 18 in^2
2. Formula: b * h ÷ 2
5 * 8 = 40 ÷ 2 = 20 ft^2
I could only help on two. Hope it helps though! =)
For the last part, you have to find where
attains its maximum over
. We have

so that

with critical points at
such that





So either

or

where
is any integer. We get 8 solutions over the given interval with
from the first set of solutions,
from the set of solutions where
, and
from the set of solutions where
. They are approximately





