Figuring out the purchases of fast food

You re sent out to pick up some refreshments for the guys working on a project. You ve gotten their orders and collected the money, but you ve lost the piece of paper with the exact listing of what everyone wants. Good thing you know how to solve word problems with numbers of items and cost per item. Math saves the day, yet again. 

The Problem You collected a total of 25 for hamburgers and soft drinks. The hamburgers cost 2.50 each, and the soft drinks cost 1.50 each. Also, the number of hamburgers ordered is three less than twice as many soft drinks. How many hamburgers and how many soft drinks were ordered  

Write two equations — one involving the number of each item times its respective cost, and the other involving the total number of items ordered. Let the number of hamburgers be represented by h and the number of soft drinks be represented by d. Multiplying h by 2.50 and d by 1.50, the total for the whole order is 2.50/i + 1.50d = 25. The number of hamburgers, h, is three less than twice the number of soft drinks, 2d - 3. Set h = 2d-3. Now replace the h in the first equation with 2d-3 and solve for h. 

So 5 soft drinks were ordered. The number of hamburgers is 2(5) - 3= 10-3 = 7 hamburgers. Five soft drinks at 1.50 each is 7.50. Seven hamburgers at 2.50 each is 17.50, for an order that totals 25. 

The Problem Last night, the Fish House Diner sold some crab-cake dinners and shrimp baskets for a total of 705. The crab-cake dinners cost 9, and the shrimp baskets cost 11.50. If you multiply the number of crab-cake dinners by three and add it to twice the number of shrimp baskets, you get 180 dinners. How many of each were sold  

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