x + 2y + 3z = 73....................(1)
3x + 2y + 10z = 195...............(2)
-x - y - z = -31........................(3)
You can solve these by elimination:-
First add equations (1) and (3) to eliminate x:-
y + 2z = 42.......................(4)
Now multiply equation (1) by -3:-
-3x - 6y - 9z = -219 Now add this to equation (2) this gives:-
-4y + z = -24.....................(5)
multiply this by -2:-
8y - 2z = 48......................(6) Now add this to equation 4 to eliminate z:-
9y = 90
y = 10
and from equation 4:-
10 + 2z = 42
2z = 32
z = 16
Now to find value of x plug in y = 10 and z = 16 into equation (1):-
x + 2(10 + 3(16) = 73 giving x = 73 - 20 - 48 = 5
Answer is x = 5, y = 10 and z = 16
