Answer:
The amount that William has at the beginning is $37.50 and the amount that Gracie has at the beginning is $52.50
Explanation:
Let
x ---> amount that William has at the beginning
y ---> amount that Gracie has at the beginning
we know that
William says to Gracie, "If you give me $7.50,we will have and equal amount of money
so
![x+7.50=y-7.50](https://img.qammunity.org/2021/formulas/mathematics/middle-school/m59rfdxhmyhx0lkx2gmoumsuq80wwl8w2c.png)
----> equation A
"Grace responds, if you give me $ 7.50 instead, I will have twice as much money as you
![2(x-7.50)=(y+7.50)](https://img.qammunity.org/2021/formulas/mathematics/middle-school/xo4fc2zvop7yur2v95t3jl367tcovpmj8m.png)
![2x-15.00=y+7.50](https://img.qammunity.org/2021/formulas/mathematics/middle-school/3fiw3fi3uenno4b0d4hpwruqia1cwwkf90.png)
----> equation B
substitute equation A in equation B
![2x-(x+15.00)=22.50](https://img.qammunity.org/2021/formulas/mathematics/middle-school/h2epuh3ty3ozaduqqfzmdtgw9vvhqng7zh.png)
solve for x
![x=22.50+15.00=37.50](https://img.qammunity.org/2021/formulas/mathematics/middle-school/ayn8tjjh4xbu3fb6n7rtzo9wq0gyfy102z.png)
Find the value of y
![y=37.50+15.00=52.50](https://img.qammunity.org/2021/formulas/mathematics/middle-school/4lnti3mmwdneojtfp96hhpny5io9jh8n91.png)
therefore
The amount that William has at the beginning is $37.50 and the amount that Gracie has at the beginning is $52.50