Hi Amey.
I see you've posted a lot of percent problems.
To do percent problems it's best to convert the percent to a decimal. We do that by dividing by 100, so 8% = 8/100 = .08.
.08x = .04y
so x = .5y meaning x is 50% of y
Then
.2x = .2(.5)y
.2x = .1y
20% of x is 10% of y