The number of fiction books are 7 and number of non fiction books are 3 respectively
let
number of fiction books = x
number of non fiction books = y
x = 4y - 5
Total books = z
x = 70% of z
y = 30% of z
x + y = z
4y - 5 + 30%(z) = z
4y - 5 + 0.3z = z
4y - 5 = z - 0.3z
4y - 5 = 0.7x
4y - 5 = 0.7z
4(0.3z) - 5 = 0.7z
1.2z - 5 = 0.7z
-5 = 0.7z - 1.2z
-5 = - 0.5z
z = -5/-0.5
z = 10
Therefore,
the number of non fiction = 30% of z
= 0.3 × 10
= 3
number of fiction = 70% of z
= 0.7 × 10
= 7
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