How much cold water at a temperature of 8 • C should be added to 80 liters of hot water at a temperature of 90 • C

How much cold water at a temperature of 8 • C should be added to 80 liters of hot water at a temperature of 90 • C to prepare a bath at a temperature of 30 • C?

As a result of heat exchange, hot (Q1) and cold (Q2) water give off the same amount of heat:
Q1 = Q2
cm1 (t2-t1) = cm2 (t2-t1) | cancel both sides by c
m1 (t2-t1) = m2 (t2-t1)
80 * (90-30) = m2 * (30-8)
80 * 60 = m2 * 22
m2 = 4800/22 = 218.2 l
Answer: 218.2 L