tolong dijawab dengan tepat

X / A = 5 hari => X = 5A

X / (A+B) = 4 hari
5A / (A+B) = 4
5A = 4A + 4B
A = 4B

X / B = ? hari
5A / B = ? hari
5 * 4B / B = ? hari
20 = ? hari

Jawab C