Step-by-step explanation:
2× (4x-5y) = 21
3x+10y= -53
-------------------------
8x-10y = 42
3x+10y=-53
------------------------
11x= -11
{x=-1}
-----------------
x=-1
3(-1)+10y=-53
-3+10y=-53
10y= -50
{y=5}
