Question

If 2x + 3y = 17 and 3x + 4y = 24, then what is 5x +7y?

Answer 1

`color(indigo)(5x + 7y = (5 * 4) + (7 * 3) = 41`

Explanation:

`2x + 3y = 17, " Eqn (1)"`

`6x + 9y = 51, color(red)(" Eqn (3) = 3 * Eqn (1)"`

`3x + 4y = 24, " Eqn (2)"`

`6x + 8y = 48, color(red)(" Eqn (4) = 2 * Eqn (2)"`

`6x - 6x + 9y - 8y = 51 - 48, color(purple)(" Eqn (3) - Eqn (4)"`

`y = 3`

Substituting value of y in eqn 91),

`2x + 9 = 17`

`2x = 8, x = 4`

`color(indigo)(5x + 7y = (5 * 4) + (7 * 3) = 41`