Question

(a) Find the sum of:
$\frac{1}{7},(\frac{2}{3}\times \frac{5}{2}),\frac{-5}{12}$

(b) If $\frac{-5}{7}=\frac{x}{28}$. Find $x$

(c) Simplify $\frac{3}{7}÷\left(\frac{21}{-55}\right)$
[3 MARKS]

Answer 1

Each part: 1 Mark

(a) $\frac{1}{7}+(\frac{2}{3}\times \frac{5}{2})+\frac{-5}{12}$

$\frac{1}{7}+\left(\frac{5}{3}\right)-\frac{5}{12}$

$\frac{12+140-35}{84}$ (LCM of 7, 3, 12 = 84)

$\frac{117}{84}$

(b) $\frac{-5}{7}=\frac{x}{28}$

$\frac{x}{28}=\frac{-5}{7}$

$x=\frac{28\times (-5)}{7}=4\times (-5)=-20$


(c) $\frac{3}{7}÷\frac{21}{-55}$

$\Rightarrow \frac{3}{7}\times \frac{-55}{21}$

$\Rightarrow \frac{1}{7}\times \frac{-55}{7}$

$\Rightarrow \frac{-55}{49}$