Two Numbers with a Sum of 18 and a Difference of 2

Define variables:
Let x = larger number and y = smaller number
Resulting system of equations:
x + y = Sum
x − y = Difference
Solve the system of equations for x (larger number):
x =  

Sum + Difference/2

Find x by substituting given Sum and Difference into equation for x and simplify:
x =  
x =  
x =  10
Solve the system of equations for y (smaller number):
y =  

Sum − Difference/2

Find y by substituting given Sum and Difference into equation for y and simplify:
y =  
y =  
y =  8
Therefore, the two Numbers are 10 and 8
Check Sum of the two Numbers:

	1	0
		8
	1	8

10 + 8 = 18 ✓
Check Difference between the two Numbers:

	0	10
	1	0
−		8
		2

10 − 8 = 2 ✓