Answer:
10 weeks, Substituion Equation.
Explanation:
(Assume that x= 'per week').
We can write this as 50 + 25x=y for Heather's savings, &
200 + 10x=y for Alssa's savings.
We can combine these equations to make 200 +10x= 50+25x, because we know 50+25x=y, like we found out in the first equation. We can now subtract 25x from each side, and subtarct 200 from each side, to get
10x - 25x = 50 - 200, which can be simplified to -15x=-150. If we divided each side by -15, we get 10. Therefore, it will take 10 weeks for them to have the same amount of money. I think this is the Substituaion Equation