tentukan himpunan penyelesian SPLDV dengan cara subsitusi a.4x+2y=8 dan x-2y=4 b.5a- b=3 dan a+b=2

a)
4x + 2y = 8 ...(i)
x - 2y = 4  atau x = 2y + 4 sub ke (i)
4(2y +4) = 8
8y + 16 = 8
8y = -8
y = - 1

x = 2y + 4
x = 2(-1) + 4 = -2 + 4
x = 2

(x,y) = (2, - 1)

(b)
5a - b = 3  atau b = 5a - 3 sub ke  a +  b =  2
a + 5a - 3 = 2
6a = 5
a = 5/6

b  = 5a - 3
b = 5(5/6) - 5
b = 25/6 - 5
b = -5/6

(a, b) = ( 5/6, - 5/6)