Ann's daily wage is $10 less that Bill's. So she has to work 4 days more than Bill to earn the same amount of money as Bill. If Bill earns $480, find Ann's daily wage.

I created a table like so,

Ann Bill

Wage (x-10) x

Days (y+4) y

Salary (x-10)(y+4) 480

Then, using the equation,

(x-10)(y+4) = 480

I got,

2x - 5y = 20

I can't seem to figure out how to proceed. What am I missing? Do I have to make an assumption of the number of days?

Thanks.