Question

Mark needs 2 3/4 cups of sugar to make cookies he has 1 7/8 cups of sugar how much more sugar does mark need

Answer 1

so, we have the denominators of 4 and 8, thus our LCD will just be 8, but let's firstly convert the mixed fractions to improper fractions and find their difference.

`\bf \stackrel{mixed}{2(3)/(4)}\implies \cfrac{2\cdot 4+3}{4}\implies \stackrel{improper}{\cfrac{11}{4}}~\hfill \stackrel{mixed}{1(7)/(8)}\implies \cfrac{1\cdot 8+7}{8}\implies \stackrel{improper}{\cfrac{15}{8}} \\\\[-0.35em] ~\dotfill\\\\ \cfrac{11}{4}-\cfrac{15}{8}\implies \stackrel{\textit{using LCD of 8}}{\cfrac{(2)11~~-~~(1)15}{8}}\implies \cfrac{22-15}{8}\implies \cfrac{7}{8}`