Please answer the following:

In E. coli there are 

(a) There are 61 codons that encode different amino acids (triplets
for amino acids)
(b) 79 different tRNAs 
(c) These 79 tRNAs contain 42 different anticodons 
(d) Thus, theoretically, 61-42 = 19 codons will not find a
complementary anticodon in the tRNA collection.

How then does E. coli construct proper polypeptides if some of the
codons cannot locate tRNAs with complementary anticodons? Explain your
answer clearly.

I think there are more than one way to do it, but just give me one. It
doesn't have to be too long. I must have the answer before 8:00 AM EST
Friday 12/9 though. I need something prepared in case my instructor
calls on me in class during discussion. I really don't want look like
an idiot in front of my peers, so please help. Thanks.

If your textbook mentions "wobble hypothesis," that section should
give you the answer.

In case your textbook doesn't mention "wobble," search google for

"more codons than trnas"

(quotes included). You should get two sites. In both you have to
scroll down to get to the part that addresses the problem. To me, the
first site

http://www.ncbi.nlm.nih.gov/books/bv.fcgi?rid=mcb.section.863

gives a better explanation; note: you need to click on Figures 4-27
and 4-28a to see them. Also, you might scroll down to the summary and
click on Table 4-2 and notice a relationship between some codon /
amino acid correspondences and the wobble hypothesis.

The second site seems to be a condensation of the first site but
doesn't explain the material as much.