2m + 4s = 66. 4m + 3s = 84. (Double the 2 glass of milk and 4 snack bars) 4m + 8s = 132. 4m + 3s = 84. (Take away the second equation from the first equation) 5s= 48. s = 48/5. s = 9.6. 4m + 3(9.6) = 84. 4m + 28.8 = 84. 4m = 84 - 28.8. 4m = 55.2. 4m/4 = 55.2/4. m = 13.8. In a glass of milk, there are 13.8 carbs, and in a snack bar, there are 9.6 carbs. 2(13.8) + 4(9.6) = 66.