Two Numbers with a Sum of 99 and a Difference of 73

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 =  86
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 =  13
Therefore, the two Numbers are 86 and 13
Check Sum of the two Numbers:

	8	6
	1	3
	9	9

86 + 13 = 99 ✓
Check Difference between the two Numbers:

	8	6
−	1	3
	7	3

86 − 13 = 73 ✓