Question 775347
This will be easier if you pick a number for c.  Pick a simple number c=100.<P>
If the cost was 100, then a 25% (.25) profit comes from 125.  That's 100(1+.25).<P>
10% profit comes from 110.
125(1+x)=110 where x is the discount number we seek.<P>
125 + 125x = 110<P>
125x=-15<P>
x = -15/125 = -.12.  We need a 12% discount on the $125 TV in order to obtain $110, which is a $10 profit.  125*(1-.12) = 110