Answer:
Hi! You just have to take his salary as a unity (one) and substract the fractions you are given. For example; lets say you have a cake (one) and then you eat 1/8 of it. You would be left with [tex]1-\frac{1}8}[/tex] of the original cake.
Step-by-step explanation:
Salary: [tex]1[/tex]
Spent [tex]\frac{2}{5}[/tex] : [tex]1-\frac{2}{5}[/tex]
Spent [tex]\frac{1}{4}[/tex]: [tex]1-\frac{2}{5} -\frac{1}{4}[/tex]
Spent [tex]\frac{1}{8}[/tex]: [tex]1-\frac{2}{5} -\frac{1}{4} -\frac{1}{8}[/tex]
REMAINING: [tex]1-\frac{2}{5} -\frac{1}{4} -\frac{1}{8}[/tex]
Operate using LCM: [tex]\frac{40-16-10-5}{40} = \frac{9}{40}[/tex]
The answer is (d)
