If you're seeing this message, it means we're having trouble loading external resources on our website.

If you're behind a web filter, please make sure that the domains *.kastatic.org and *.kasandbox.org are unblocked.

# Scale drawing: centimeters to kilometers

Sal uses ratios to figure out how far apart two cities should be on a map. Created by Sal Khan.

## Want to join the conversation?

• so... basically you just do x6 to both? .
• yes its like equivalent fractions.you know when you multiply the numerator and the denominater by the same number.
• So basically the number you multiply by depends on the ratio between the scale factor and the other number?
• Yes, it is.
• I got this question and I'm not sure how to solve it
A 17 Oz box of Special K for \$4.89 or a 21 Oz box of Cheerios for \$5.69. Which is the better deal?
Thanks
• Your problem is a typical problem involving unit prices. The better deal is the one with the lowest unit price. You can calculate any unit price by doing: Price ÷ Units (in this case ounces). So, here are the steps you need to do.
1) Calculate the unit price for the Special K: 4.89 ÷ 17
2) Calculate the unit price for the Cheerios: 5.69 ÷ 21

Here's a video on unit prices: https://www.khanacademy.org/math/pre-algebra/pre-algebra-ratios-rates/pre-algebra-rates/v/finding-unit-prices

Hope this helps.
• I did the "ratio word problems" by the way at below :
for example :
Laine reads 25 pages in 30 minutes.
If Laine reads 200 pages in a same rate, how long will it take her?
I did like this: 25=30
200=?
I used 200*30 then divide 25 and the answer is 240 which is an correct answer.
Can I find any answers from this type of question by the solution above?
Thank you.
• Yes, this is a correct way to solve ratio problems. ( and 200:? would be the correct way to write it. 25 does not equal 30.)
• I have no idea what this man just said
• maybe re-watch it again.
• This really isnt neccessary is it?
• It might be
(1 vote)
• Im still really confused