In this task, you need to answer the given multiple-choice question on the physics. Classify your answers into 'a', 'b', 'c', 'd', and 'e'.

Problem: if 4 spiders make 3 webs in 9 days , then how many days are needed for 1 spider to make 1 web ? 
Options: a ) 9 , b ) 12 , c ) 27 , d ) 24 , e ) 16
b

Problem: a can do a piece of work in 18 days and b alone can do it in 10 days . b works at it for 5 days and then leaves . a alone can finish the remaining work in 
Options: a ) 5 days , b ) 6 days , c ) 7.5 days , d ) 8.5 days , e ) 9 days
e

Problem: working alone at its constant rate , machine a produces x boxes in 10 minutes and working alone at its constant rate , machine b produces 2 x boxes in 5 minutes . how many minutes does it take machines a and b , working simultaneously at their respective constant rates , to produce 10 x boxes ? 
Options: a ) 13 minutes , b ) 14 minutes , c ) 15 minutes , d ) 16 minutes , e ) 20 minutes

e