Luis is finding 9-6+2. find his mistake and correct it : 9-8= 1

He is adding 6 + 2 to get 8.

However, he should add -6 and 2, to get -4.

He can then use 9+-4 = 9-4 = 5.

Alternatively, he could do:

9 - 6 = 3

3 + 2 = 5

The discount is 8.70 . you dont tell us the percent of tax added so there is no way to find out, unless i'm not seeing anything. without tax its 37.70