tolong dibantu nomor 8 yah poin banyak kalau gak jelas angkanya bisa tanya lewat pwsan jangan lewat jawaban, makasih.. :)

a.
→ Mencari x :
k = (x + 5) + (x + 7) + 8
40 = x + 5 + x + 7 + 8
40 = 2x + 20
2x = 40 - 20
2x = 20
x = 20/2
x = 10

b.
→ Mencari x :
k = (x + 6) + (x + 6) + (x + 6)
63 = 3x + 18
3x = 63 - 18
3x = 45
x = 45 / 3
x = 15