The value of x in this system of equations is 1. 3x y = 9 y = –4x 10 substitute the value of y in the first equation: combine like terms: apply the subtraction property of equality: apply the division property of equality: 3x (–4x 10) = 9 –x 10 = 9 –x = –1 x = 1 what is the value of y?

We have two unknowns from the equation therefore, two equations are needed. These equations are:

3x + y = 9
y = –4x +10 

To solve for y, we first substitute the second equation to the first one.
3x + –4x +10= 9 
x = 1

We substitute the value of x to either of the equations and solve for y.

y = –4(1) +10 
y = 6

Repeating the steps of the statement:

3x + y = 9
y = -4x + 10

3x -4x + 10 = 9
-x + 10 = 9
-x = 9-10
-x = -1
x=1 (the same value given in the first sentence of the statement).

y = -4x + 10 (second equation of the system)
y = -4 (1) + 10 = -4 + 10 = 6

y = 6