Answer: $17.92/sandwich
Step-by-step explanation:
Let S be the price of a sandwich ($/sandwich).
7S is the total cost of the sandwiches. Add a drink for $2.50 to find the total cost, which we are told comes to $140.50
7S + $2.50 = $140.50
7S = $138
S = $19.7143
It is odd that this includes a fraction of a single penny (0.43 cents). Something is incorrect in the data given, since this should equal a whole number. For now, I'll round up to $19.72. The additional 7*($0.0043) = 4 cents will be treated as a tip.
