Two Numbers with a Sum of 30 and a Difference of 7

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 =  
30 + 7/2

x =  
37/2

x =  18.5
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 =  
30 − 7/2

y =  
23/2

y =  11.5
Therefore, the two Numbers are 18.5 and 11.5
Check Sum of the two Numbers:
11
18.5
11.5
30.0
18.5 + 11.5 = 30 (trailing zero and decimal point are dropped) ✓
Check Difference between the two Numbers:
18.5
11.5
7.0
18.5 − 11.5 = 7 (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.

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