# Math Help - opposite increase decrease

1. ## opposite increase decrease

hello

when an amount is increased by x%, what percentage y% is needed to decrease the increased amount in the initial amount?

for example 100 is increased by 5% and becomes 105
in which percentage is needed to decrease 105 to 100?

is there an equation that can calculate this?

thanks

2. $\frac{5}{105}\times 100$