Answer:
Her first error was adding the wrong number to both sides. Instead of 4², it should be 2²
Step-by-step explanation:
When completing the square, the number that needs to be added to both sides is (b/2)²
In this problem, b is 4. So, Carly should have added 2² to both sides, but she added 4² instead.
So, her first error was adding 4² to both sides instead of 2²
<h3>
Answer: 78.6</h3>
Work Shown:

Multiply across the rows to form a third column. Example: 9*90 = 810 in the first row.

The values in the third column add to 810+1440+1050 = 3300
Divide this over the total number of people which is 9+18+15 = 42
The mean is 3300/42 =78.571 approximately which rounds to 78.6
0.85$ for 1 cups
1$ for 1/0.85 cups
55.25$ for [1/0.85]*55.25 = 55.25/0.85 = 65 cups