4 specials and 2 glasses of milk = $28.00. 3 specials and 4 glasses of milk = $26.25. How much does it cost for 2 specials and 2 glasses of milk?
Accepted Solution
A:
First, we should write the equation system of the problem s stands for special, m stands for milk ⇒ 4s + 2m = 28.00 (first equation) ⇒ 3s + 4m = 26.25 (second equation)
Solve the first and second equation using elimination method. I'm going to eliminate m, so we can calculate s. 4s + 2m = 28.00 (multiply 2) 3s + 4m = 26.25 (multiply 1) ------------------------------------- 8s + 4m = 56.00 3s + 4m = 26.25 ----------------------- - (substract) 5s = 30.25 s = 6.05
I'm using subtitution method to find m. Subtitute 6.05 as s to one of the equation. 4s + 2m = 28.00 4(6.05) + 2m = 28.00 24.20 + 2m = 28.00 2m = 3.80 m = 1.90
The cost for a glass of milk is $1.90 and a special is $6.05
Calculate cost for 2 specials and 2 glasses of milk 2s + 2s = 2(6.05) + 2(1.90) = 12.10 + 3.80 = 15.90
The cost for 2 specials and 2 glasses of milk is $15.90