Consider the equation
1) First row of the table
Set x=0 and solve as follows:
The answer is y=20 and the pair x-y is (0,20)
2) Second row
Set x=1 and solve, as follows:
The answers are y=10 and (1,10)
3) Third row.
Set y=0 and solve as follows:
The answers are x=2 and (2,0)