Question 682965
<pre>
Let x = The number of students majoring in math ONLY

let y = The number of students majoring in computer science ONLY

Let z - The number of students majoring in computer science.

{{{(matrix(8,1,

The,number, of,students, majoring, in, math, ONLY))}}} + {{{(matrix(11,1,

The,number, of,students, majoring, in, BOTH,math,AND,computer,science))}}} ={{{(matrix(7,1,

The,number, of,students, majoring, in, math))}}} 


{{{(matrix(9,1,

The,number, of,students, majoring, in, computer, science, ONLY))}}} + {{{(matrix(11,1,

The,number, of,students, majoring, in, BOTH,math,AND,computer,science))}}} ={{{(matrix(8,1,

The,number, of,students, majoring, in, computer, science))}}}


{{{(matrix(8,1,

The,number, of,students, majoring, in, math, ONLY))}}} + {{{(matrix(11,1,

The,number, of,students, majoring, in, BOTH,math,AND,computer,science))}}} +{{{(matrix(9,1,

The,number, of,students, majoring, in, computer, science, OMLY))}}} = {{{(matrix(13,1,

The,TOTAL,number, of,students, majoring, in, math, or, computer, science, or, both))}}}

So we substitute the corresponding numbers or unknowns for
the above three statements and we have this system of equations:

x + 120 = 300
y + 120 = z
x + 120 + y = 540

Solve that and get x = 180, y = 240, and z = 360

The answer asked for was z, which is 360.

Edwin</pre>