X's income is $75\%$ of Y's income, and X's expenditure is $80\%$ of Y's expenditure. lf X's income is $90\%$ of Y's expenditure, then find the ratio of X's savings to Y's savings.

My Alliance India phone bill for the month of May is $₹\mathrm{B}$. On top of this, there is a service tax of $\mathrm{S}\%$, which has to be levied upon this value. However, since they are having a guilt feeling of overcharging their customers fraudulently, they offer a discount of $\mathrm{D}\%$ also on top of this. So, my billing goes like this $₹ \mathrm{B}\to \mathrm{S}\%\uparrow \to \mathrm{D}\%\downarrow \to$ Final Bill

But surprisingly, my final bill is equal to $₹\mathrm{B}$ itself. Now, which of the following is true regarding $\mathrm{S}$ and $\mathrm{D}$ (assume all the values to be positive)?

Assuming percentage to be true for all the real values, which of the following can be true?

$40\%$ of $\mathrm{A}=60\%$ of $\mathrm{B}$

(i) $\mathrm{A}>\mathrm{B}$

(ii) $\mathrm{B}>\mathrm{A}$

(iii) $\mathrm{B}=\mathrm{A}$