Find two numbers that have a sum of 77.95 and a difference of 30.61

If you would like to know the values of these two numbers, you can calculate this using the following steps:

a + b = 77.95
a - b = 30.61 ... a = 30.61 + b

a + b = 77.95
(30.61 + b) + b = 77.95
30.61 + 2 * b = 77.95
2 * b = 77.95 - 30.61
2 * b = 47.34    /2
b = 47.34 / 2
b = 23.67

a = 30.61 + b = 30.61 + 23.67 = 54.28

Result: The numbers are 23.67 and 54.28.