Question

There is $2\frac{3}{4}lb$ of cheese in the kitchen. Your mother used $2\frac{3}{5}lb$ of cheese to make a sandwich. How much cheese is left?

• A. $\frac{5}{20}lb$
• B. $\frac{3}{20}lb$
• C. $\frac{2}{20}lb$
• D. $\frac{4}{20}lb$

Answer 1

The correct option is B $\frac{3}{20}lb$

Total quantity of cheese in the kitchen $=2\frac{3}{4}lb$
Quantity of cheese used to make a sandwich $=2\frac{3}{5}lb$
Quantity of cheese left $=2\frac{3}{4}lb-2\frac{3}{5}lb$
$2\frac{3}{4}-2\frac{3}{5}=\frac{2\times 4+3}{4}-\frac{2\times 5+3}{5}=\frac{11}{4}-\frac{13}{5}=\frac{11\times 5}{4\times 5}-\frac{13\times 4}{5\times 4}=\frac{55}{20}-\frac{52}{20}=\frac{55-52}{20}=\frac{3}{20}$
Remaining quantity of cheese $=\frac{3}{20}lb$