# How do you solve the system of equations 5x + 4y = 60 and 8x + 7y = 99?

Jul 2, 2018

color(red)(x = 8, y = 5

#### Explanation:

$5 x + 4 y = 60 , \text{ Eqn (1)}$

$8 x + 7 y = 99 , \text{ Eqn (2)}$

$7 \cdot \text{ Eqn (1)" - 4 * " Eqn (2)}$

$35 x + 28 y - 32 x - 28 y = 420 - 396$

3x = 24 " or x = 8

Substituting value of 'x' in Eqn (1),

$5 \cdot 8 + 4 y = 60$

$y = \frac{60 - 40}{4} = 5$