Diketahui sistem persamaan: 2x + 3y = 13 3x - 4y = -23 Nilai 4x - 5y adalah...?

Eliminasikan:
2x + 3y = 13 -------->> (dikali 3)
3x - 4y = -23 -------->> (dikali 2)
____________ 

6x + 9y = 39
6x - 8y = -46
____________ -
17y = 85
y = 5

Subtitusikan y ke:
2x + 3y = 13
2x + 3(5) = 13
2x + 15 = 13
2x = 13 - 15
2x = -2
x = -2/2
x = -1

Nilai 4x - 5y adalah:
= 4x - 5y
= 4(-1) - 5(5)
= -4 - 25
= -29