Answer: it will take 9 weeks for them to have the same amount in their account.
Explanation:
Let x represent the number if weeks it will take for them to have the same amount in their savings account.
Bethany has $120 in her savings account and spends $8 a week at the candy store. It means that the amount that she would have in her account after x weeks is
120 - 8x
Johnny has $75 in his savings account and spends $3 a week at the candy store. It means that the amount that she would have in her account after x weeks is
75 - 3x
For both amounts to be the same, the number of weeks would be
120 - 8x = 75 - 3x
- 3x + 8x = 120 - 75
5x = 45
x = 45/5
x = 9