Answer: the minimum number of weeks is 7
Explanation:
Let x represent the number of weeks that Thomas walk the dog.
Tom is going to save money for the ticket by walking his neighbor's dog for $15 per week. if Tom already has save $22, it means that the total amount that he would have saved if he walks the dog for x weeks is
15x + 22
A prom ticket at Smith high school is $120. Then, the expression for the minimum number of weeks that Thomas would walk the dog to earn enough to pay for the prom ticket is
15x + 22 ≥ 120
15x ≥ 120 - 22
15x ≥ 98
x ≥ 98/15
x ≥ 6.5
Since the number of weeks must be whole number, then x = 7