Question 741736
What about dishes of ice cream and milk shakes? Bad question!!

.9c+1.65s=180.54,
c+s=148
something is wrong with the question. 
c~~84.88,   s~~63.12
c and s must be positive integers.
c=85 and s=63 yields 
.90*85+1.65*63=180.45
 The total should be 180.45 not 180.54
There is no way to get a total of 180.54 with prices 90 and 1.65