Ale drawings
a missing side length in a scale drawing when given either a set of corresponding side
Sororeside length and the scale factor
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A scale on a map shows that 3 centimeters represents 10 kilometers.
What number of centimeters on the map represents an actual distance of 25 kilometers?

So the first thing we do is to multiply the top equation by 3. the reason i want to do this is i notice there will be a 6y on both equations and can possibly add/subtract them. so we get 6y = -3x + 27. adding that and the second equation we get 6x = 27-15 which is 12. divide by 6 and we get 2. ∴ x = 2. substituting 2 into the first equation we get 2y = -2 + 9 which is 7. divide by 2 and we get 7/2. ∴ y = 7/2, x = 2.

12