Question 1000698
Two groups of students order burritos at a mexican restaurant. 
One order of 3 burritos and 4 tacos cost $11.33 and the other 
order of 9 burritos and 5 tacos costs $23.56. How much will it 
cost to buy 5 burritos and 7 tacos?
<pre>
 3B + 4T = 11.33
 9B + 5T = 23.56

Solve by elimination:

Multiply the first equation by -3 to get -9B where the 3B is
so that it will cancel with the 9B when the equations are added.

-9B - 12T = -33.99
 9B +  5T =  23.56
------------------
      -7T = -10.43
        T = $1.49

Substitute in 

      3B + 4T = 11.33
 3B + 4(1.49) = 11.33
    3B + 5.96 = 11.33
           3B = 5.37
            B = $1.79

A taco costs $1.49 and a burrito costs $1.79.

Therefore 5 burritos and 7 tacos will cost 

5B + 7T = 5($1.79) + 7($1.49) = $19.38

Edwin</pre>