Unit Conversion using Algebraic Techniques

Unit conversion is one of those concepts of my Educational life which consumed huge amount of brain energy and time. But i was successful in finding the solution which is working most of the time for me. Its lengthy but accurate and error free.
First of all you have to memorize all some basic units like 
1m=3.2ft=39.2inch   or 
1kg=2.2lbs
.
.
.
.


then just by simple substitution and simplification we can get to the answer.

I have checked all the answers form www.wolframalpha.com/‎      they are correct but i am fishy about the iii) example. There is some mistake in it but the method is same.

 Download in PDF:
http://www.mediafire.com/download/yhsrba2kgek5e2r/Unit_Conversions.pdf