A box contains some lemons, mangoes and oranges. 0.8 of the lemons is equal to 70% of the mangoes. The number of oranges is ⁵₇ of the total number of mangoes and lemons. If there are 171 less mangoes than oranges, how many fruits are there in the box altogether?

Lemons	Mangoes	Oranges
7x7	8x7
7x15		5x15
49 u	56 u	75 u

0.8 = ⁸₁₀= ⁴₅
70% = ⁷⁰₁₀₀ = ⁷₁₀

0.8 of the lemons is equal to 70% of the mangoes. Make the numerators the same.  LCM of 4 and 7 is 28.

4x75x7 of the lemons = 7x410x4 of the mangoes
2835 of the lemons = 2840 of the mangoes 

Lemons : Mangoes
35 : 40 _(÷5)
7 : 8

The total number of lemons and mangoes is repeated.  Make the total number of lemons and mangoes the same.  LCM of 15 and 7 is 105.

Number of less mangoes than oranges
= 75 u - 56 u
= 19 u

19 u = 171

1 u = 171 ÷ 19 = 9

Number of the fruits in the box altogether
= 49 u + 56 u + 75 u
= 180 u
= 180 x 9
= 1620

Answer(s): 1620