How to do the ninth item on page 60 of the sixth grade of People's Education Edition?
This is a question about who is Unit 1. First of all, the width of No.7 is 850MM, which is 2/ 15 higher than No.6. That is to say, (No.7 width-No.6 width)/No.6 width =2/ 15.
So the width of No.6 = 850 ÷ (1+215), which means 6: 7 =1:(1+215) =1:.