Tolong dijawab klo bisa pakai cara nya mau dikumpulkan, terimakasih.

a) 4x - 15y = - 4
6x + 5y = 5 |×3
maka
4x - 15y = - 4
18x + 15y = 15
---------------------(+)
22x = 11
x = ½
subtitusi
4x - 15y = - 4
4(½) - 15y = - 4
2 - 15y = - 4
- 15y = - 4 - 2
- 15y = - 6
y = -6/-15
y = 2/5
nilai 2x + 5y
= 2(½) + 5(2/5)
= 1 + 2
= 3


b) ½x + ⅔y = - 5 ( dikalikan 6)
maka
3x + 4y = - 30
¼x + 1/12y = - 1 ( dikalikan 12)
maka
3x + y = - 12
eliminasi
3x + 4y = - 30
3x + y = - 12
---------------------(-)
3y = - 18
y = - 6
subtitusi
½x + 2/3y = - 5
½x + 2/3(-6) = - 5
½x - 4 = - 5
½x = - 5 + 4
½x = - 1
x = - 2
nilai 2x + 5y
= 2(-2) + 5(-6)
= - 4 - 30
= - 34