CANDIDATE A
18-34 53.7%
35-64 37.3%
65+ 8.9%
CANDIDATE B
18-34 17.6%
35-64 47.1%
65+ 35.3%
If 2x+y=5, then y=5-2x, so she substituted correctly.
x+4x=5x, so she combined like terms correctly.
She didn't subtract 10 from both sides, she added 10 to both sides.
Check the solution:

The answer is: She made no mistake.
Answer:
11/12
Step-by-step explanation:
2/3+1/4
8+3/12
=11/12