(a) The cost of one set of curtains, shade, and rods is the sum of the costs of these separate items:
... set cost = c + 1/9c + 1/9c -7 = (1 2/9)c -7
Then the cost of 2 sets is ...
... 2 × set cost = 2((1 2/9)c -7) = (2 4/9)c -14 = 22c/9 -14
(b) Putting 382.50 into this expression where "c" is, then doing the arithmetic, gives ...
... cost of 2 sets = 22·382.50/9 -14 = 8415/9 -14 = 935 -14 = 921 . . . . dollars