Please assist me with this problem.

Answer:
Step-by-step explanation:
a) The retail price (r) is the wholesale price (w) plus 20% of that price plus $2.50:
r = w + 0.20w + 2.50
r = 1.20w + 2.50
__
b) Substituting w=8.40, we have ...
r = 1.20·8.40 +2.50 = 12.58
The retail price of the chair is $12.58.
__
c) Substituting r=13.30, we have ...
13.30 = 1.20w +2.50
10.80 = 1.20w . . . . . . . subtract 2.50
9.00 = w . . . . . . . . . . . . divide by 1.20
The wholesale price of the chair is $9.00.