Find the value of two numbers if their sum is twelve and their difference is 4. Please explain to me how to do this and what the answer is!



Answer :

So,

All you have to do is to translate the words into open sentences with placeholders.

Apparently, there are 2 numbers, call them x and y.

Now, build open sentences.
x + y = 12
x - y = 4

Now, which method will we use to solve?  I choose Elimination by Addition.

Add the equations together.
2x = 16

Divide both sides by 2
x = 8

Substitute
8 + y = 12

Subtract 8 from both sides.
y = 4

Check

The sum of the two numbers is 12 (8 + 4).

The difference of the two numbers is 4 (8 - 4).

The first number is 8.
The second number is 4.