Ruben bought 6 new book which increased his collection by 12%. how many books did he have?

The initial number of books he had=50

The number of books he has after adding new books=56

Step-by-step explanation:

Step 1: Derive formula for percentage increase

The formula for calculating the percentage increase is;

p={(f-i)/i}×100

where;

p=the percentage increase

f=the final number of books he had

i=the initial number of he had

In our case;

p=12%

(f-i)=defines the increase in the number of books=6

i=unknown

Substitute and solve for i;

12%=6/i

(12/100)=6/i

(12/100)×i=6

i=6×100/12

i=50

The initial number of books he had=50

The number of books he has after adding new books=50+6=56

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step-by-step explanatio89