Question 268429
8 t-shirt for $17 means $2.125 / T-shirt 
5% off means that 95% still remains. 95% of $2.125 = $2.02
3 more t-shirts at $2.02 = $6.06
----
If he sells only the 3 t-shirts at a markup of 15%, then
1.15* $2.02 = $2.32
3 x $2.32 = $6.69
The different between new and original is 30 cents
---