Question

Solve the system using the substitution method 3x-y=4 5x+3y=9

Answer 1

First solve the first equation for 'y'
3x - y = 4  subtract 3x from both sides
-y = -3x + 4  divide both sides by -1
y = 3x - 4   Now take this equation and substitute into the second equation:

5x + 3y = 9
5x + 3(3x - 4) = 9
5x + 9x - 12 = 9
14x - 12 = 9
14x = 9 + 12
14x = 21
x = $\frac{21}{14} = \frac{3}{2}$ or 1.5
Now substitute this value for 'x' into either of the first two equations to find 'y'
I'll use the equation 
y = 3x - 4
y = 3(1.5) - 4
y = 0.5

So your solution is (1.5, 0.5)