### Theory:

A human body is made up of face, hands, legs and so on.

Similarly, a bill is also made up of various components.
Point 1: A bill always has the name of the shop mentioned on top.

Point 2: A unique number is given to each of the bills. It is called the bill number or the serial number of a bill. It helps us find that particular bill easily. No two bill of the same shop will have the same bill number.

Point 3: The date mentioned on the bill is called the date of purchase.

Point 4: The list of items purchased are always given under the Items column.

Point 5Quantity is the total number of each item bought. Quantity can either be in numbers or weights. For example, one notebook or $$1$$ kilogram of rice. In this case, the notebook is quantified in numbers, and rice is quantified in weights.

Point 6: The cost of each item or the rate of each item is the original price of each item.

Point 7: Amount to be paid for each item is quantity multiplied by the rate of each item.

Point 8: The total amount to be paid for the entire purchase is the addition of amounts to be paid for each of the items.

Bill Number: $$120$$

Date: $$1-12-2020$$

 S. No. Items Quantity(in nos.) Rate(per item) Amount(in $$Rs.$$) 1 Notebook $$3$$ $$10$$ $$30$$ 2 Pen $$2$$ $$5$$ $$10$$ 3 Pencil $$4$$ $$2$$ $$8$$ 4 Ruler $$1$$ $$7$$ $$7$$

Total amount to be paid: $$Rs.55$$
Let us analyze each of the components of the bill in detail.
According to the bill, the name of the shop is 'XYZ Stationery Store'. It is located somewhere in 'Tamil Nadu'.

The bill number is $$120$$.

The date of purchase is $$1-12-2020$$.

The list of items purchased include notebook, pen, pencil and ruler.
The quantity of each item denotes the number of items purchased.
From the given bill, $$3$$ notebooks, $$2$$ pens, $$4$$ pencils and $$1$$ ruler has been purchased.

Rate of $$1$$ notebook $$= Rs.10$$

Rate of $$1$$ pen $$= Rs.5$$

Rate of $$1$$ pencil $$= Rs.2$$

Rate of $$1$$ ruler $$= Rs.7$$
Amount is the what we get when we multiply quantity with rate.
$$\text{Amount}$$ $$=$$ $$\text{Quantity}$$ $$×$$ $$\text{Rate of each item}$$

The amount to be paid for notebooks $$= 3$$ $$×$$ $$10 = Rs.30$$

The amount to be paid for pens $$= 2$$ $$×$$ $$5 = Rs.10$$

The amount to be paid for pencils $$= 4$$ $$×$$ $$2 = Rs.8$$

The amount to be paid for rulers $$= 1$$ $$×$$ $$7 = Rs.7$$
The total amount to be paid for the purchase is got when we add the amount to be paid for each of the items.
According to this bill:

The total amount to be paid $$=$$ Amount to be paid for the notebooks $$+$$ Amount to be paid for the pens $$+$$ Amount to be paid for the pencils $$+$$ Amount to be paid for the rulers

$$= 30 + 10 + 8 + 7$$

$$= Rs.55$$

Important!
Tax deductions: Tax is nothing but the amount to be paid to the government. The government uses this money to run the country and provide public services to people. The public services include police, army and so on.