2 kids had the same number of cars.  After she gave him 72 cars, he had 3 times as many cars as her.  How many stickers did they have in all?

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beckden's profile pic

beckden | High School Teacher | (Level 1) Educator

Posted on

At the start 'she' has x cars and 'he' has x cars.

If 'she' has x cars then she has x-72 cars when she gives them to 'him'.

Now 'he' has three times as many cars as 'she', so he has 3(x-72) cars.

But since they both had x cars to begin with, this must be equal to x+72 after 'she' has given him 72 cars.

So now we have an equation

3(x-72)=x+72

Distribute

3x-216=x+72

2x=216+72     subtract x from both sides, and add 216 to both sides

2x=288     divide both sides by two

x=144   So they started out with 144 cars

So they both had 144 cars this means they started out with 288 cars.

qwertymak's profile pic

qwertymak | Student, Grade 10 | (Level 1) Honors

Posted on

Let the two kids be A & B

Both had equal number of cars so we assume that

A=x cars & B=x cars

after A gives cars to B

A=x-72 & B=x+72

It is given that B had three times as many cars as A

=> 3*(x-72) = x+72

=> 3x-216 = x+72

=> 3x-x = 72+216

=> 2x= 288

=> x= 144

Therefore in all they had 144+144 cars= 288 cars

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