how to solve distance ratio

Question

How do you solve Donna drives 800 miles in 3 days. At this rate, how many miles will she drive in 15 days?

 

The answer is 4000 miles but I don't understand thier formula for getting that answer

they said D=15000 I couldn't figure that out

 

Thank you

melissa baker

Answer 1

Simple proportion.

15 days is 5 times 3 days so the distance she travels is 5 times as much as 800 miles=4000 miles.

Use simple logic rather than trying to remember formulas, which often distract you from finding the answer. This is why many people find mathematics difficult. They try to memorise lots of formulas when it isn't necessary, so they make it difficult for themselves trying to look for or remember them.