# How do you solve the system of equations by using substitution: x - 2y = 0 and 2x - 5y = -4?

Nov 7, 2016

$x = 8$ and $y = 4$

#### Explanation:

Step 1) Solve the first equation for $x$ while keeping the equation balanced:

$x - 2 y = 0$

$x - 2 y + 2 y = 0 + 2 y$

$x = 2 y$

Step 2) Substitute $2 y$ for $x$ in the second equation and solve for $y$:

$2 \left(2 y\right) - 5 y = - 4$

$4 y - 5 y = - 4$

$- y = - 4$

$\frac{- y}{-} 1 = \frac{- 4}{-} 1$

$y = 4$

Step 3) Substitute $4$ in the solution for $y$ in the first equation.

$x = 2 \cdot 4$

$x = 8$