A farmer planted 5000 grains of maize and harvested 5000cobs, each bearing 500 grains. What is the ratio of the number of grains sowed to the number harvested?

If $m:n=13:11$find $({{m}^{2}}-{{n}^{2}}):{{(m+n)}^{2}}$

Simplify $\tfrac{3}{5}\div (\tfrac{2}{7}\times \tfrac{4}{3}\div \tfrac{4}{9})$

Simplify $7\tfrac{1}{12}-4\tfrac{3}{4}+2\tfrac{1}{2}$

A student spent $\tfrac{1}{5}$of his allowance on books, $\tfrac{1}{3}$of the reminder on food and kept the rest for contingencies. What fraction was kept.

Simplify $\frac{3\tfrac{2}{3}\times \tfrac{5}{6}\times \tfrac{2}{3}}{\tfrac{11}{15}\times \tfrac{3}{4}\times \tfrac{2}{27}}$

Simplify $1\tfrac{2}{3}+4\tfrac{1}{4}\div 1\tfrac{5}{12}$

Evaluate $\frac{{{27}^{\tfrac{1}{3}}}-{{8}^{\tfrac{2}{3}}}}{{{16}^{\tfrac{2}{4}}}\times 2}$

Evaluate $5\tfrac{1}{3}\times 7\tfrac{1}{4}\div \tfrac{116}{27}$

$\frac{\tfrac{2}{3}\div \tfrac{4}{5}}{\tfrac{1}{4}+\tfrac{3}{5}-\tfrac{1}{3}}$