Answer:
x = -2, y = 5 and z = 7 in that order
Step-by-step explanation:
first number = x
second number = y
third number = z
Process
1.- Write equations to solve this problem
x + y + z = 10 Equation l
2y - x = 12 Equation ll
x - y + 2z = 7 Equation lll
2.- Solve equation ll for x
x = 2y - 12
3.- Substitute the previous equation in equation l and lll
(2y - 12) + y + z = 10 (2y - 12) - y + 2z = 7
2y - 12 + y + z = 10 2y - 12 - y + 2z = 7
3y + z = 10 + 12 y + 2z = 19
3y + z = 22
4.- Solve for y and z
-2(3y + z = 22)
y + 2z = 19
-6y - 2z = -44
y + 2z = 19
-5y + 0 = -25
y = -25/-5
y = 5
-Find z
5 + 2z = 19
2z = 19 - 5
2z = 14
z = 14/2
z = 7
5.- Find x
x + 5 + 7 = 10
x = 10 - 5 - 7
x = -2
