Question

$\frac{1}{3} + \frac{1}{4} =$$\frac{1}{3} + \frac{2}{4}$=$\frac{9}{10} - \frac{7}{20} =$ 
$\frac{11}{18} + \frac{5}{12}$=
$\frac{4}{21} + \frac{1}{4}$

Answer 1

$\frac{1}{3} + \frac{1}{4} = \frac{(4*1)+(3*1}{12} = \frac{4+3}{12} = \frac{7}{12}$

$\frac{1}{3} + \frac{2}{4} = \frac{(4*1)+(3*2}{12} = \frac{4+6}{12}= \frac{10}{12}= \frac{5}{6}$

$\frac{9}{10} - \frac{7}{20} = \frac{(2*9)+7}{20} = \frac{18+7}{20}= \frac{25}{20}= \frac{5}{4}$

$\frac{11}{18} - \frac{5}{12} = \frac{(2*11)+(3*5)}{36} = \frac{22+15}{36}= \frac{37}{36}$

$\frac{4}{21} - \frac{1}{4} = \frac{(4*4)+(21*1)}{84} = \frac{16+21}{84}= \frac{37}{84}$