tolong ya guys soal mtk

sepeda motor = s > beroda 2
becak = b > beroda 3
mobil = m > beroda 4

2s + 3b + 4m = 68

b + m = 11

b = s - 9


b + m = 11
s - 9 + m = 11
s + m = 11 + 9
m = 20 - s

2s + 3b + 4m = 68
2s + 3(s - 9) + 4(20 - s) = 68
2s + 3s - 27 + 80 - 4s = 68
s + 53 = 68
s = 68 - 53
s = 15

b = s - 9
= 15 - 9
= 6

jumlah becak = 6 (D)