Question

Replace and $mns{q}^2$ in each of the following by the correct number :
(a) $\frac{2}{7}=\frac{8}{\square }$ (b) $\frac{5}{8}=\frac{10}{\square }$
(c) $\frac{3}{5}=\frac{\square }{20}$ (d) $\frac{45}{60}=\frac{15}{\square }$
(e) $\frac{18}{24}=\frac{\square }{4}$

Answer 1

$a)\frac{2}{7}=\frac{8}{\square }$

cross multiplying

$2\times \square =7\times 8$

$\square =\frac{7\times 8}{2}$

$\square =7\times 4$

$\square =28$

so$\frac{2}{7}=\frac{8}{28}$

$b)\frac{5}{8}=\frac{10}{\square }$

$5\times \square =8\times 10$

$\square =\frac{8\times 10}{5}$

$\square =8\times 2$

$\square =16$

so$\frac{5}{8}=\frac{10}{16}$

$c)\frac{3}{5}=\frac{\square }{20}$

cross multiplying

$20\times 3=\square \times 5$

$5\times \square =3\times 20$

$\square =\frac{20\times 3}{5}$

$\square =4\times 3$

$\square =12$

$d)\frac{45}{60}=\frac{15}{\square }$

cross multiplying

$45\times \square =15\times 60$

$\square =\frac{15\times 60}{45}$

$=\frac{60/3}{3/3}$

$\square =20$

$e)\frac{18}{24}=\frac{\square }{4}$

cross multiplying

$18\times 4=\square \times 24$

$\square =18\times 4$

$\square =\frac{18\times 4}{24}$

$\square =\frac{18/2}{6/2}$

$\square =\frac{18/2}{3/3}$

$\square =3$