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 $160.50 for 4 burgers, 10 shakes, and one cola. How much would it cost for a meal of one burger, one shake, and one cola? Select:
A) $21  B) $27  C) $31  D) $39  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=160.5   Subtracting the first equation from the second gives us B+3S=40.5   Now if we subtract the new equation two times from first or 3 times from second we will get B+S+C=39. In any case, there is no necessity to know each item's price, just the sum.   Answer: $39
<result>D</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 $160.50 for 4 burgers, 10 shakes, and one cola. How much would it cost for a meal of one burger, one shake, and one cola?