Problem 2 - percentages

The price of a phone has increased by 10%. After a month the price of the phone dropped by 20%. What was the price of the phone before the price changes if the phone now costs $ 1100?

Fill in here

Exemple !

The price of a phone has increased by 25%. After a month the price of the phone dropped by 20%. What was the price of the phone before the price changes if the phone now costs $ 1000?

We note with y the unknown value.

We find out the price before it drops

20/100
y = y - 1000

80y/100
= 1000

80y = 100000

y = 1250

Verification

20/100
x 1250 =
25000/100
= 250

1250 - 250 = 1000

We find out the price before it increase

25/100
y + y = 1000

125y/100
= 1250

125y = 125000

y = 1000

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