How much water should be mixed with 237 ml of ammonia, whose strength is 100%, in order to create a mixture that is diluted to a 75% strength?

Answer

79 ml

Explanation

You have 237 237 ml of ammonia, whose strength is 100%.

If you want to make it 75%, then;

let 75%  ⇒ 237 ml of ammonia and

   25% ⇒  x ml of water.

∴ x = (25% ×237) / 75%

       = 5,925/75

         = 79 ml of water.

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