Two Numbers with a Sum of 21 and a Difference of 8

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 =  
21 + 8/2

x =  
29/2

x =  14.5
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 =  
21 − 8/2

y =  
13/2

y =  6.5
Therefore, the two Numbers are 14.5 and 6.5
Check Sum of the two Numbers:
11
14.5
6.5
21.0
14.5 + 6.5 = 21 (trailing zero and decimal point are dropped) ✓
Check Difference between the two Numbers:
014
14.5
6.5
8.0
14.5 − 6.5 = 8 (trailing zero and decimal point are dropped) ✓

The solution above and other related solutions were provided by the Find two Numbers given Sum and Difference Application.

Curated Videos