Find the values of x and y using the simultaneous equations: x+y=11, y-6=15

First solve the equation with only one unknown to find y:y-6=15Add 6 to both sides to get the value of y:y=15+6y=21Now there is only one unknown we can solve for x:x+21=11x=11-21x=-10Check the values are correct by substitution:-10+21=11