The two numbers add up to 50.5, and one number is 9.5 less than the other. Find the second number.

Let x be the first number and y the second number. By the condition of the problem, we know that the sum of the first and second numbers is – 50, 5. So the equation will look like this:
x + y = 50.5.
Also, by the statement of the problem, we know that one number is 9.5 less than the other. I.e:
x – 9.5 = y.
Substitute this value into the first equation:
x + y = 50.5.
x – 9.5 = y.
x + x – 9.5 = 50.5.
2x – 9.5 = 50.5.
2x = 50.5 + 9.5.
2x = 60.
x = 60/2.
x = 30 – the first number.
Find out what the second number is equal to:
x – 9.5 = y.
30 – 9.5 = y.
20.5 = y is the second number.
Answer: the second number is 20.5.