x+5y=21

x+3y=11

x=21-5y (isolate x)

sub the value of x to 2nd equation to solve for y

21-5y+3y=11

-2y=-10

y=5

substitute the value of y into the other equation to solve for x

x+5(5)=21

x+25=21

x=-4

Do you see what I did? Now follow the same method for solving the second one and show me what you get