Question

A box full of black and White pens has 85 black pens.if 7/24 of all pens in the box are white pens,how many pens are there in the box?
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Answer 1

Let total number of white and black pens be x.

Total number of black pens = 85

proportion of white pens = 7/24

proportion of black pens = 1 - 7/24 = 17/24

According to statement

17/24 of x = 85

x = 85 × 24/17 = 120

So 120 pens are there in the box.