There are 12 eggs in a dozen. We can set up a cross-multiplication problem to solve this. 12/100=3.5/x
3.5 times 100 is 350, or two decimal places to the right. 12 times x is 12x. Now we can solve for x.
12x=350
divide 12 on both sides to isolate x.
350 divided by 12 is 29.1666667
so 3.5 is 29.66666667 of 12.