Jeremy is opening a savings account earning simple interest. he plans to deposit his $50 birthday money and leave the account alone until he goes to college. he will earn $5 per year in interest.

10%

Step-by-step explanation:

Use the formula of simple interest:

We can determine the interest rate if he earns $5 a year. Which means after a year he will have $55. Let A be the final amount after year t with t=1:

Solve for r, the interest rate:

Jeremy will earn money in the firsts year at a interest rate of 10%

a and c

for infinitely many solutions we require both left and right sides to be equal

distribute and simplify

a

14 - 8x = 20 - 8x - 6 = 14 - 8x ← both sides equal so infinite solutions

b

6x - 54 = 6x - 54 + x = 7x - 54 ← not equal

c

4x + 16 = 4x + 10 + 6 = 4x + 16 ← both sides equal so infinite solutions

d

5x - 40 + 10 = 5x + 10

5x - 30 = 5x + 10 ← not equal