If y = -x and x + 6y = 30, what is the
value of x?

x = -6

Step-by-step explanation:

y = -x  equation 1

x + 6y = 30   equation 2

using equation 1 in equation 2 we have:

x + 6(-x) = 30

x - 6x =30

-5x = 30

x= -30/5

x= -6