Question

a number is first increased by 20 and then 15 find the net increase or decrease percent

Answer 1

Let the no. Bex
Then by increasing it by 20% it will become 120% of itself=120x/100=6x/5
Then by increasing the result by 15% will give 115/100 of it
=115/100×6x/5
=1.38x
Increase =.38x
Original number=x
%increase =.38x/x×100
=38%

Answer 2

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• Let the Number be 100.

➟ 100 × (100 + 20)% × (100 - 15)%

➟ 100 × 120% × 85%

➟ 100 × $\large\tt{\frac{120}{100}}$ × $\large\tt{\frac{85}{100}}$

➟ 100 × $\large\tt{\frac{12}{10}}$× $\large\tt{\frac{17}{20}}$

➟ 10 × 12 × $\large\tt{\frac{17}{20}}$

➟ 102%

2% increase