Jason H. answered • 03/27/19
Passionate Stem and Test Prep Tutor Who Teaches for Mastery
First let me ask, how many miles would one inch represent? Well, the question I would ask myself would be what operation would I use to get from half an inch to one inch? I would multiply by 2. (1/2)*2 = 1.
Then, according to equation rules, if we multiply something by one side, we have to multiply the exact same thing on the other side for the equation to still hold. So if (1/2) inch = 10 miles, (1/2)*2 inch= 10*2 or 20 miles.
Now using the same logic, what do I do to get from half an inch to 4 and 1/2 inches? I would multiply by 9. So if (1/2) inch= 10 miles, (1/2)*9 inches = 10*9 or 90 miles.
Another way to think about it would be, how do I get from 1/2 inch to 10 miles? I multiplied by 20. Thus, as ratios hold, I must multiply 4 and 1/2 by 20 as well to get to how many miles the towns are from each other. 4 and 1/2 * 20 is 90 miles.
