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

Question

1795 views around the world

You can reuse this answer
Creative Commons License

Answer 1 · 2018-07-02T08:57:32

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

$5 x + 4 y = 60, Eqn (1)$ $5x + 4y = 60, " Eqn (1)"$

$8 x + 7 y = 99, Eqn (2)$ $8x + 7y = 99, " Eqn (2)"$

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

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

$3 x = 24 or x = 8$ $3x = 24 " or x = 8$

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

$5 \cdot 8 + 4 y = 60$ $5 * 8 + 4 y = 60$

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

How do you solve the system of equations 5x+4y=605x + 4y = 60 and 8x+7y=998x + 7y = 99?