To fill a tank measuring 20 cm by 70 cm by 25 cm completely, it takes Tap S 40 minutes while it takes Tap T only 40 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 7 cubic containers of edges 13 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 
= 20 x 70 x 25
= 35000 cm³
= 35000 mℓ

Volume of 7 containers
= 13 x 13 x 13 x 7
= 15379 cm³ 
= 15379 mℓ

Remaining volume to be filled by the Tap S and Tap T 
= 35000 - 15379
= 19621 mℓ
= 19621 cm³

Fraction of the tank to be filled
= ¹⁹⁶²¹₃₅₀₀₀
= ¹³⁸³₂₄₆₇

Tap S:
1 tank → 40 min
1 min → ¹₄₀ tank

Tap T:
1 tank → 40 min
1 min → ¹₄₀ tank

Tap S and Tap T:
1 min → ¹₄₀ + ¹₄₀ = ¹₄₀ + ¹₄₀ = ¹₂₀ tank

1 tank = ²⁰₁ min

¹³⁸³₂₄₆₇ tank = ²⁰₁ x ¹³⁸³₂₄₆₇ = ²⁸⁰³₂₅₀ = 11.212

Answer(s): 11.21 min