Question

The sum of two numbers is 12. The difference of the same two numbers is −4. Find the two numbers.

Answer 1

Answer: x = 4, y = 8

Explanation:

Let the two numbers be x and y

sum of the two numbers will be

x + y = 12 ------------------------------1

Difference of the two numbers

x - y = -4 ----------------------------- 2

Now, to find the two numbers , we solve equation 1 & 2 together

x + y = 12

x - y = -4

we now add the two equations to eliminate y

2x = 8

x = 4. Now to find the value of y, we substitute for x in any of the equation above

x + y = 12

4 + y = 12

y = 12 - 4

y = 8

Answer 2

4 and 8

Explanation:

Let 'a' represent one of the numbers. Then the other is 12-a, and their difference is ...

a - (12-a) = -4

2a = 8 . . . . add 12

a = 4 . . . . . divide by 2

12-a = 8 . . . . find the other number

The two numbers are 4 and 8.