If 7 spiders make 7 webs in 7 days, then 1 spider will make 1 web in how many days?  Select the correct option.
A) 8	B) 6	C) 7	D) 5	E) 1
Explanation:   Let the required number days be x.   Less spiders, More days (Indirect Proportion)   Less webs, Less days (Direct Proportion)   {\color{Blue} therefore } 1 x 7 x x = 7 x 1 x 7   =&gt; x= 7   Answer: 7
<result>C</result>
If 7 spiders make 7 webs in 7 days, then 1 spider will make 1 web in how many days?