You can put this solution on YOUR website! I can!...but first, since you wrote "5y=10x=20" did you really mean to write: or ???
I suspect the latter is what you meant so I'll use that, but if I'm wrong, please resubmit with the appropriate correction.
Solve:
1)
2)
Substitute equation 1) for y into equation 2) to get:
2a) Simplify and solve for x.
2a)
2a)
2a)
2a) Now substitute this value of x into equation 1) and find y.
1) Substitute
1) Evaluate the right side.
1)
1)
The solution: (-1/2, 5)