A number is first decreased by 20%. The decreased number is then increased by 20%. The resulting number is less than the original number by 20. Then the original number is ?
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15
Let the original number is x.
If it is decreased by 20%,
20%of x = 20/100 * x = 0.2x
the new number = x - 0.2x = 0.8x
If the new number is increased by 20%,
20%of 0.8x = 20/100 * (0.8x) = 0.16x
the new number = 0.8x + 0.16x = 0.96x
The resulting number is less than original number by 20
So x - 0.96x = 20
⇒ 0.04x = 20
⇒ 4x/100 = 20
⇒ x = 20*100/4 = 500
The number is 500
If it is decreased by 20%,
20%of x = 20/100 * x = 0.2x
the new number = x - 0.2x = 0.8x
If the new number is increased by 20%,
20%of 0.8x = 20/100 * (0.8x) = 0.16x
the new number = 0.8x + 0.16x = 0.96x
The resulting number is less than original number by 20
So x - 0.96x = 20
⇒ 0.04x = 20
⇒ 4x/100 = 20
⇒ x = 20*100/4 = 500
The number is 500
Jahnvi97:
Thanks Nazee
Answered by
14
Let the number be x
therefore, 20% of x = 20/100 * x = x/5
then after decreasing the no is x - x/5 = 4x/5
then, 20% of 4x/5 = 4x/25
then after increasing the no. is 4x/5 + 4x/25 = 24x/25
A/q
x - 20 = 24x/25
x - 24x/25 = 20
x = 500
so, the original no. is 500
I HOPE IT HELPFUL FOR YOU.....
therefore, 20% of x = 20/100 * x = x/5
then after decreasing the no is x - x/5 = 4x/5
then, 20% of 4x/5 = 4x/25
then after increasing the no. is 4x/5 + 4x/25 = 24x/25
A/q
x - 20 = 24x/25
x - 24x/25 = 20
x = 500
so, the original no. is 500
I HOPE IT HELPFUL FOR YOU.....
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