Question

Вычислите:
1)1/2 + 4/7 + 7/12; 2) 1/5 + 3/8 - 3/9

Answer 1

$frac{1} {2}+frac{4} {7}+frac{7} {12}$
$=frac{42+12+7} {84}=frac{61} {84}$

$frac{1} {5}+frac{3} {8}-frac{3} {9}$
$=frac{8+15} {40}-frac{3} {9}=frac{23}{40}+frac{3}{9}$
$=frac{207}{360}-frac{120}{360}=frac {87}{360}$