The trip is in 36 weeks. Jessie needs to save the exact same amount of money (lets call this “x”) for 36 weeks to get 3060 dollars (I assume) by the end of these 36 weeks.
So, really, Jessie will just be adding the same amount of money to the amount he saved the previous week, and do this 36 times. This would be “x+x+x+x+...” 36 times, or 36x.
He needs to have 3060 by the end of this, so that would mean:
36x = 3060
x = 3060/36
x = 85
He will need to save 85 dollars weekly.