Question

Read the paragraphs and answer the following questions. (A) The repetition of sound caused by the reflection of sound waves is called an echo. When a person shouts in a big empty hall, we first hear his original sound. After a little while, we hear the reflected sound of shout. This reflected sound' is an 'echo'. So, when we hear an echo, we are actually hearing a reflected sound, a short while after the original sound. Thus an echo is simply a reflected sound. 68.When sound gets reflected from a surface: @the angle of incidence<angle of reflection
B the angle of incidence=angle of reflection
c the angle of incdence>angle of reflection d)None of the above​

Answer 1

Answer:

option d is the right answer

Answer 2

Answer:

$x + y = 25 \\ \\ y = 20 \\ \\ x = 5$