Question

Rajan bought $21$ burgers each costing $Rs136$ to treat his friends. His mother bought $15$ plates of fruit salad each costing $Rs75$ for them. Rajan and his friends ate burgers and only 2 plates of fruit salad. How much money was spent in all and how much money was wasted? Which is more healthy: fruit salad or burgers?

Answer 1

Hint: Denote the unknown quantity by some letters. If the value of one unit is given then we can find the necessary value by multiplying the single unit value and if the value of multiple items is given to us, we simply divide the total value by the number of units to obtain the value of one unit.

Complete step-by-step answer:
According to question,
Let the total money spend be $Rs.x$ and
The total money wasted be $Rs.y$
Cost of one burger= $Rs136$
Therefore, cost of $21$ burgers= $Rs(21 \times 136)$
= $Rs2,856$.
Cost of one plate of fruit salad= $Rs75$
Therefore, cost of $15$ plates of fruit salad= $Rs(15 \times 75)$
= $Rs1,125$.
As total money spend be $Rs.x$
Hence,
Total money spent in all= Cost of $21$ burgers + Cost of $15$ plates of fruit salad
$ = Rs(2,856 + 1,125)$
$ = Rs3,981$
As only 2 plates of fruit salad were eaten by Rajan’s friend.
Therefore, cost of $2$ fruit salad= $Rs(2 \times 75)$
= $Rs150$
Also, the total money wasted be $Rs.y$
 So, total money wasted= Cost of $15$ fruit salad -Cost of $2$ fruit salad
= $Rs(1,125 - 150)$
$ = Rs975$
$\therefore $Total money spent in all $ = Rs3,981$ and,

Total money wasted $ = Rs975$

Note: The method by which we find out the value of one unit and further use it to find the value of multiple units is known as unitary method. In essence, if the value of multiple items is given to us, we simply divide the total value by the number of units to obtain the value of one unit.