5x + y = 10
3x - 2y = 6
ok
The question mentions that we need to leave alone y in the first equation.
5x + y = 10 Just pass 5x to the other side of the equation
if it has a positive sign, we change the sign to a negative
one.
that's all
y = -5x + 10 This is the answer
Letter B is the correct answer