Explanation

Let's start by calling the two numbers we are looking for x and y.

x + y = 80

x - y = 20

x - y = 20

x = 20 + y

x + y = 80

20 + y + y = 80

20 + 2y = 80

2y = 60

y = 30

x + y = 80

x + 30 = 80

X = 50

Sum: 50 + 30 = 80

Difference: 50 - 30 = 20

Explanation

 Although the units for sound intensity are technically watts per meter squared, it is much more common for it to be referred to as decibels, dB.

A decibel is a ratio of the observed amplitude, or intensity level to a reference, which is 0 dB.

Explanation

Deuterium, (D, or 2H), also called heavy hydrogen.

Deuterium is an isotope of hydrogen.

In the simple hydrogen molecule, 

there is one proton,

one electron,

and no neutrons,protons,electrons,

and neutrons being the elementary particles that make up the atom.).

while 

Deuterium, on the other hand, is composed of one proton, one electron, and one neutron.

ND11-07-2023

Explanation

As the person is 7th from the either end, implies, there are 6 persons ahead of him and 6 persons behind him as shown below. Hence, there are 13 persons in the queue.

Explanation

The given series is a square of natural number

(1)^2 = 1

(2)^2 = 4

(3)^2 =9

(4)^2 = 16

(5)^2 = 25

(6)^2 = 36

(7)^2 = 42

(8)^2 = 64

Explanation

b=12, c−a=8

a2+b2=c2

⇒b2=(c−a)(c+a)

⇒144=8×(c+a)

Solving we get, c = 13 cm, a = 5cm

Area of triangle =21×12cm×15cm=30cm2

Explanation

The difference between consecutive terms of the given series are respectively 5, 7, 9, 11 and 13.

Clearly, 34 is a wrong number and must be replaced by (24 + 11) i.e. 35.