Two Numbers with a Sum of 20 and a Difference of 5

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 =  12.5
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 =  7.5
Therefore, the two Numbers are 12.5 and 7.5
Check Sum of the two Numbers:

	1	1
	1	2	.	5
		7	.	5
	2	0	.	0

12.5 + 7.5 = 20 (trailing zero and decimal point are dropped) ✓
Check Difference between the two Numbers:

	0	12
	1	2	.	5
−		7	.	5
		5	.	0

12.5 − 7.5 = 5 (trailing zero and decimal point are dropped) ✓