After x weeks:
Jules will have: 1,200 + 40 x.
Kelsey will have: 400 + 50 x.
If we want to know in how many weeks will they have the same amount of money, we will make an equation:
400 + 50 x = 1,200 + 40 x
50 x - 40 x = 1,200 - 400
10 x = 800
x = 800 : 10
x = 80
Answer: In 80 weeks they will have the same amount of money.
