Answer:
4b
Step-by-step explanation:
Factor 80.
80 = 4 * 4 * 5 * b * b
Since there are two 4s and bs, they can be taken out of the square. (Because if you put a square root over 4 squared or b squared, you would get 4 or b.)
Now you are left with 4b.
The first one f(x) = -1/3x + 5
$135
10% of 150 = 15
150 - 15 = 135