They approved 20% off of the $20.00 item so .20*20 = $<<20*.01*20=4.00>>4.00
The item has a $4.00 discount which can be applied from his final total of $54.00 so 54-4 = $<<54-4=50.00>>50.00
Now he can use his 10% coupon on the $50.00 total so .10*50 = $<<10*.01*50=5.00>>5.00
The total was $50.00 but his $5.00 discount now makes it 50-5 = $<<50-5=45.00>>45.00
#### 45