Questions

Let the missing numbers be x, y, a and b

x + y = 8 ---- (1)
a - b = 6 ---- (2)
x + a = 13 --- (3)
y + b = 8 ---- (4)

2x + a + y = 21 --- From (1 & 3)
a + y = 14 ----  From (2 & 4)

Substitute (2 & 4) in (1 & 3)

2x + 14 = 21
2x = 7
x = 3.5

From (1) ---> 3.5 + y = 8
=> y = 8 - 3.5 = 4.5

a + y = 14 => a = 14 - y = 14 - 4.5 => a = 9.5
From (4) ---- y + b = 8 => b = 8 - y = 8 - 4.5 = 3.5

Hence,
x = 3.5
y = 4.5
a = 9.5
b = 3.5

Radon gas is a source of natural groundwater pollution.

A spreadsheet is an interactive computer application for organization, analysis and storage of data in tabular form. This software allows users to store data in rows and columns.

In India, country's 1st Owl Festival held in Pune, for two days i.e, on Nov 29 and Nov 30. It is a first-of-its-kind festival in the country that is being organised with the intention of creating awareness about owl as a bird and debunking numerous superstitions associated with it.

Government is to set to introduce new Rs. 100 coin with image of former Prime Minister Atal Bihari Vajpayee.

The Bill of Rights established the rights of citizens. It is also called as Declaration of rights or Charter of rights. It is a list of most important rights to the citizens of a country.

The 2nd largest consumer and importer of the LPG in the worldis India.

These are called intrusive igneous rocks because the magma has intruded into pre-exiting rock layers. Types of intrusive igneous rocks are granite and basalt .

A batholith is the largest of the intrusive bodies.