You and a friend go to the local taco joint for lunch. You order three tacos and three burritos and your bill totals $11.25. Your friend's bill is $10.00 for 2 burritos and 4 tacos. Which system of equations can be used to determine the cost of b, a single burrito, and t, a single taco? 
 A. 
3t + 3b = 10 
2t + 4b = 11.25 
B. 3t+ 3b = 11.25
 2t + 4b = 10 
C. 3t+ 3b = 10
 4t + 2b = 11.25
D. 3t + 3b = 11.25 
 4t + 2b = 10