How many calories are in each sandwich and each cookie

Question

John ate 2 sandwiches and 3 cookies for a total of 1342 calories. Sarah ate 1 sandwich and 2 cookies for a total of 777 calories. How many calories are in each sandwich and in each cookie?

Answer 1

Let x = the number of calories in a sandwich

Let y = the number of calories in a cookie

2x + 3y = 1342

1x + 2y = 777       x = 777 - 2y

2(777 - 2y) + 3y = 1342

1554 - 4y  + 3y = 1342

-y = -212

y = 212 calories

x = 777 - 2(212) = 777 - 424

x = 353 calories