Answer:
6 training sessions.
Explanation:
Let there be x training sessions at both the gyms.
At silver gym,
Total cost = membership + personal training session
= 25+45x ...(1)
At Fit Factor,
Total cost = 85+35x ....(2)
If the total cost at the two gyms equal,
25+45x=85+35x
Taking like terms together,
45x-35x=85-25
10x=60
x = 6
Hence, Sarah must buy 6 training sessions.