If 1 inch = 150 miles, we can use fractions (ratios) to determine what 3 1/2 inches would be
Since 1 is correlated to 150, they would be on the same fraction
1/150 (it really doesn’t matter which one is on top and which one is on the bottom)
And since 1 and 3 1/2 are both inches, they both go on the same side of the fraction. X would be a placeholder value for the miles
1/150 = 3.5/x
Multiply x
x • 1/150 = 3.5
Divide by 1/150 or multiply by 150 (they are the same in this case)
x = 525 miles
Or, more simply in this case, just multiply 3.5 inches by 150 miles
3.5 • 150 = 525 miles