Solving a proportion with an unknown variable (example) | 7th grade | Khan Academy

Here's a great video where we explain the reasoning behind solving proportions. We'll put some algebra to work to get our answers, too.

Missed the previous lesson?

Grade 7th on Khan Academy: 7th grade takes much of what you learned in 6th grade to an entirely new level. In particular, you'll now learn to do everything with negative numbers (we're talking everything--adding, subtracting, multiplying, dividing, fractions, decimals... everything!). You'll also take your algebraic skills to new heights by tackling two-step equations. 7th grade is also when you start thinking about probability (which is super important for realizing that casinos and lotteries are really just ways of taking money away from people who don't know probability) and dig deeper into the world of data and statistics. Onward! (Content was selected for this grade level based on a typical curriculum in the United States.)

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[caloyespinosa]

ill make things easier

8 10
--- ---
36 n

36x10=360
360 divided by 8 = 45

easy

[spork]

i wonder how this guy is doing. he's always been one of my favorite narrators. man..

[zyliththeblob]

Math is literally making me have a break down

[Gwagwa]

Who else is the sad sad 11th grader watching this video for ACT practice because you're almost an adult and you still cant do proportions

[nasty]

Thanks khan you got me through another problem thanks i finally going to get my degree im in the early stages of it but with your help im going to get this finally thanks for this math upload

[a....]

how in the world do you get these numbers

[alainesribera]

Thanks so much khan academy I have been trying to do this for hours thanks again!

[nicoleellis]

I wish someone told me that in these words when i was a kid. I did it mechanically without real understanding for years of primary school.

[yea]

I'm learning this in sixth grade.

[Joomba_Juice]

For people that are confused, there is an easier way, just multiply 36 times 10 then divide by 8. the answer will still be 45

[tedoymisojos]

Thanks you for these videos. They are so helpful.

[halahosari]

It says that this is 7th grade math but im in 6th learning this...weird 😑

[imeldamejia]

thx for the new ways of solving proportions with an unknown variable.

[wilsonfoster]

math is so hard but with khan academy its got a lot more easy then i thought.

[spencerwells]

Just cross multiply then divide the number by the variable.

[BlueArrows]

Im in gift math but got a 70 d, on this, i actually think gifted children is actually for special ed kids who teachers just want them to feel better

[hotman]

It makes sense but he makes it more complicated. The simplest way would be just to make a simple algebra equation 36x10=8n and solve for n. The way he's explaining it shows the logic behind it instead of just a formula. You are finding a number to multiply the numerator of the first fraction to match the one on the second. Then simply multiplying the denominator would give you the value of the second denominator. He makes it sound more complicated.

[chloewoo]

Sal Khan be like, you do that, then that, and that’s the answer. 🤯🤯🤯

[kiro]

Im just grade 6 and we are talking about proportions 🤪🤪🤪

[ApartmentViews]

How on earth did people find this helpful????