If 7 spiders make 7 webs in 7 days, then 1 spider will make 1 web in how many days?
Answer: C
Let the required number days be x.
Less spiders, More days (Indirect Proportion)
Less webs, Less days (Direct Proportion)
Spiders1:7Webs7:1⋮⋮ 7:x
=> 1 * 7 * x = 7 * 1 * 7
=> x= 7