Question

Your cousin buys $1\frac{4}{5}lb$ of cheese to make sandwiches. She uses $1\frac{3}{10}lb$. How much cheese does she have left?

• A. $\frac{1}{2}lb$
• B.
  $\frac{5}{10}lb$
• C. $\frac{31}{10}lb$
• D. $\frac{22}{10}lb$

Answer 1

Answer: (A), (B)

$\frac{5}{10}lb$
Total amount of cheese $=1\frac{4}{5}lb$
Cheese used for sandwiches $=1\frac{3}{10}lb$
Amount of cheese left $=1\frac{4}{5}lb-1\frac{3}{10}lb$
$1\frac{4}{5}=1+\frac{4}{5}=\frac{1\times 10}{1\times 10}+\frac{4\times 2}{5\times 2}=\frac{10}{10}+\frac{8}{10}=\frac{18}{10}$
$1\frac{3}{10}=1+\frac{3}{10}=\frac{1\times 10}{1\times 10}+\frac{3}{10}=\frac{10}{10}+\frac{3}{10}=\frac{13}{10}$
Amount of cheese left $=\frac{18}{10}-\frac{13}{10}=\frac{5}{10}lb$
$\frac{5}{10}=\frac{5÷5}{10÷5}=\frac{1}{2}lb$
Hence, both options c and d are correct.