Aditya Godavarti
1

First set up a system of two equations.


Equation 1: \frac{\left(x\ +\ y\ +\ a+\ b\right)}{4}\ =\ 350


Equation 2: x\ +\ y\ +\ a\ =\ 900


x\ +\ y\ +\ a\ +\ b\ =\ 1400 - (x\ +\ y\ +\ a\ =\ 900)


b\ =\ 500

Mahesh Godavarti
0

Since there are four items and the average number of calories per item is 350, the total number of calories across all four items is 1400.


Since the other three add up to 900 calories, the sandwich has to have 500 calories, in order for the total number of calories to be equal to 1400.