The sum of two numbers is 12. Three times the smaller number increased by the larger number is 20 . Find the numbers .Write the solution

In these types of algebra problems where we are given numbers that are "unknown" and asked to find them, it is a good idea to give them names.

Let the larger number be X.

Let the smaller number be Y.

If the larger number is three times the smaller number, we can use this information to write an equation, using our labels for the two unknown numbers. See how I translate this sentence into an equation:

The larger number is three times the smaller number.

                    X           =     3     *               Y

X = 3*Y

We've got one equation down. Since we have two variables, we're going to need two equations to solve for both of them.

The sum of two numbers is twenty-four.

                      X    +    Y    =     24

X+Y = 24

But, from our previous equation, we know that X is the same as 3*Y. This allows us to substitute "X" with "3*Y" in our second equation since the two are equal according to the first equation.

(3*Y) + Y = 24.

3Y + Y = 24

4Y = 24

4Y / 4 = 24/4

Y = 6

Now we've got the value of the smaller number. Let's plug it into our first equation,

X = 3*Y.

X = 3*(6)

X = 18

We can check our work by plugging both values into both equations and seeing if they work out:

6+18 = 24  

6*3 = 18

So our bigger number is 18, and our smaller number is 6.

Hope it helps!