Step by step
The question
Question: Mia is twice as old as Leo.
Together they are 36.
How old is each?
1 Find what we know
What do we know?
Mia is 2 times as old as Leo.
Their two ages added together make 36.
What do we want?
How old each one is.
2 Name the unknown
We know Mia's age from Leo's age.
So we start with Leo.
We call Leo's age x.
Twice means 2 times.
Mia is 2 times as old: 2x.
3 Write the equation
In words: Leo's age plus Mia's age makes the sum.
So the equation is x + 2x = 36.
Now we solve it.
4 Group like terms
Terms are the parts between the + and − signs.
Like terms are the same kind: same letters, same powers.
All the x terms go together.
x + 2x = 3x.
Now we have 3x = 36.
5 Remove the 3
3x means 3 times x.
We want just x.
To remove times 3, we divide by 3.
We do it on both sides, so they stay equal.
3 divided by 3 is 1.
So just x is left.
36 divided by 3 is 12.
So x = 12!
6 Answer the question
Mia's age is 2x: 2 × 12 = 24.
Leo is 12, Mia is 24.
7 Check
Let's check in the story.
Together: 12 + 24 = 36, like the story says.
And Mia is 2 times as old: 2 times 12 is 24.
Does it make sense?
Ages are whole numbers, more than 0.
Ours are.
So the answer is right!
Let's look back.
First: find what we know.
Then: name the unknown.
Then: write the equation.
Then: solve it.
Then: answer the question.
Last: check.