Let
and
. Then


and


The expression under the square root can be rewritten as

Recall that

so that

and assuming
and
, we end up with

so that

as required.
45÷50=90%
if that is what you are looking for
The total bill amount before the service fee is given as $45.
We are given that the tip she wants to leave is 15% of the bill amount, this means that:
tip value = 0.15 * 45 = 6.75$
The total bill would be the summation of the original bill and the tip value she left.
Total bill amount = 45 + 6.75 = 51.75$
10 cancels out so its 5/3 :) Rate Me plz <span />