Question 72658
x + 5y = 10 ________(1)
-2x - 10y = -20 ________(2)


Multiply both sides of equation (1) by 2.
Then you get
-2(x + 5y) = -2(10)
-2x - 10y = -20


This is same as equation (2).
Thus equations (1) and (2) are identical so there are infinite solutions of 'x' and 'y'.