At an upscale fast-food restaurant, Shin can buy 3 burgers, 7 shakes, and one cola for $120. At the same place it would cost $164.50 for 4 burgers, 10 shakes, and one cola. How much would it cost for a meal of one burger, one shake, and one cola?
Choose the correct choice from the following choices:
A) $21  B) $27  C) $31  D) $41  E) It cannot be determined
let's suppose that the price of a burger is BB, of a shake - SS and that of a cola is CC. We can then construct these equations:   3B+7S+C=120   4B+10S+C=164.5   Subtracting the first equation from the second gives us B+3S=44.5   Now if we subtract the new equation two times from first or 3 times from second we will get B+S+C=31. In any case, there is no necessity to know each item's price, just the sum.   Answer: $31
<result>C</result>
At an upscale fast-food restaurant, Shin can buy 3 burgers, 7 shakes, and one cola for $120. At the same place it would cost $164.50 for 4 burgers, 10 shakes, and one cola. How much would it cost for a meal of one burger, one shake, and one cola?