6 weeks.
To solve this, create an equation as so:
5.15 (15) x = 425
It is set up as so in order to incorporate given numbers and to find the missing number aka the weeks.
If using this equation, you need to first multiply 5.15 and 15. Then, your equation will turn into this:
77.25x = 425
To find x, divide 425 by 77.25. Originally, this will give you 5.5, but it's asking for weeks total and not half weeks, so round up to get 6.
Hope this helps!
