Question

At the beginning of the day the stock market goes up 30 1/2 points. At the end of the day, the stock market goes down 100 3/4 points. what is the change from the high to the end of the day?

Answer 1

Well, is namely their difference, so, let's first convert the mixed fractions to "improper", and subtract.

$\bf \stackrel{mixed}{30\frac{1}{2}}\implies \cfrac{30\cdot 2+1}{2}\implies \stackrel{improper}{\cfrac{61}{2}} \\\\\\ \stackrel{mixed}{100\frac{3}{4}}\implies \cfrac{100\cdot 4+3}{4}\implies \stackrel{improper}{\cfrac{403}{4}}\\\\ -------------------------------\\\\ \cfrac{61}{2}-\cfrac{403}{4}\impliedby \textit{so our \underline{LCD is 4}}\implies \cfrac{(2\cdot 61)~-~(1\cdot 403)}{4} \\\\\\ \cfrac{122-403}{4}\implies \cfrac{-281}{4}\implies -70\frac{1}{4}$