the The Solution.
The marked price of the 72-inch TV = $1500
25% discount makes the actual discount to be:

So, the discounted price will now be
Discounted price = 1500 - 375 = $1125
He has an additional 10% internet coupon discount on already dicounted price ($1125) .

a. The friend will save

b. in percentage, he saved

Therefore, the correct answers are:
a. $487.50
b. 32.5%