To fill a tank measuring 60 cm by 30 cm by 50 cm completely, it takes Tap P 36 minutes while it takes Tap Q only 45 minutes. How long will it take to completely fill the container with water if both the taps are turned on at the same time and 5 cubic containers of edges 9 cm, filled to the brim with water are poured into the tank? Leave your answer in minutes and round off to 2 decimal places.
Volume of the tank 
= 60 x 30 x 50
= 90000 cm³
= 90000 mℓ

Volume of 5 containers
= 9 x 9 x 9 x 5
= 3645 cm³ 
= 3645 mℓ

Remaining volume to be filled by the Tap P and Tap Q 
= 90000 - 3645
= 86355 mℓ
= 86355 cm³

Fraction of the tank to be filled
= ⁸⁶³⁵⁵₉₀₀₀₀
= ¹⁶¹¹₁₆₇₉

Tap P:
1 tank → 36 min
1 min → ¹₃₆ tank

Tap Q:
1 tank → 45 min
1 min → ¹₄₅ tank

Tap P and Tap Q:
1 min → ¹₃₆ + ¹₄₅ = ⁵₁₈₀ + ⁴₁₈₀ = ¹₂₀ tank

1 tank = ²⁰₁ min

¹⁶¹¹₁₆₇₉ tank = ²⁰₁ x ¹⁶¹¹₁₆₇₉ = ¹⁹¹⁹₁₀₀ = 19.19

Answer(s): 19.19 min