Question

Solve the following:
1) 7/10 + 2/5 + 8/21
2) 9/11 - 4/15
3) 4 + 7/8
4) 3/5 +217​

Answer 1

$\sf\huge\bold{\underline{\underline{{Solution}}}}$

$\sf \longmapsto(1) \dfrac{7}{10} + \dfrac{2}{5} + \dfrac{8}{21}$

Taking LCM of 10 & 5

LCM of 10 & 5 is 10

$\sf \longmapsto \dfrac{7 + 4}{10} + \dfrac{8}{21}$

$\sf \longmapsto \dfrac{11}{10} + \dfrac{8}{21}$

LCM of 10 & 21 is 210

$\sf \longmapsto \dfrac{23 + 80}{210} = \dfrac{103}{210}$

solving 2)

$\sf \longmapsto \dfrac{9}{11} - \dfrac{4}{15}$

LCM of 11 & 15 is 165

$\sf \longmapsto \dfrac{15 \times 9 - 11 \times 4}{165}$

$\sf \longmapsto \dfrac{135 - 44}{165}$

$\sf \longmapsto \dfrac{91}{165}$

Solving 3)

$\sf \longmapsto4 + \dfrac{7}{8}$

LCM of 1 & 8 is 8

$\sf \longmapsto \dfrac{4 \times 8 + 7}{8} = \dfrac{32 + 7}{8} = \dfrac{39}{8}$

solving 4)

$\sf \longmapsto \dfrac{3}{5} + 217$

LCM of 1 & 5 is 5

$\sf \longmapsto \dfrac{3 + 217 \times 5}{5}$

$\sf \longmapsto \dfrac{3 + 1085}{5} = \dfrac{1088}{5}$