Question

On one day a rickshaw puller earned Rs 80. Out of his earnings he spent Rs $13\frac{3}{5}$ on tea and snacks. Rs $25\frac{1}{2}$ on food and Rs $4\frac{2}{5}$ on repairs of the rickshaw. How much did he save on that day?

Answer 1

Money saved by the rickshaw puller = Total money earned - (Earnings spent on tea and snacks + Earnings spent on food + Earnings spent on repairs)
$$\begin{gathered} =80-\left(13\frac{3}{5}+25\frac{1}{2}+4\frac{2}{5}\right) \\ =80-\left(\left(13+\frac{3}{5}\right)+\left(25+\frac{1}{2}\right)+\left(4+\frac{2}{5}\right)\right) \\ =80-\left(\frac{68}{5}+\frac{51}{2}+\frac{22}{5}\right) \end{gathered}$$

$$\begin{gathered} \mathrm{Now}, \\ \frac{68}{5}+\frac{51}{2}+\frac{22}{5}=\frac{\left(68\times 2\right)+\left(51\times 5\right)+\left(22\times 2\right)}{10} \\ =\frac{136+255+44}{10} \\ =\frac{435}{10} \\ =\frac{87}{2} \end{gathered}$$

∴$\frac{68}{5}+\frac{51}{2}+\frac{22}{5}=\frac{87}{2}$
Money saved by the rickshaw puller $=80-\frac{87}{2}$
$$\begin{gathered} =80+\left(\mathrm{Additive}\mathrm{inverse}\mathrm{of}\frac{87}{2}\right) \\ =\frac{160-87}{2} \\ =\frac{73}{2} \\ =\mathrm{Rs}36\frac{1}{2} \end{gathered}$$
Therefore, the amount of money saved by the rickshaw puller is Rs $36\frac{1}{2}$.