May you also provide an explanation so I can get the concept?

Since the first ratio given is for 1 inch, for the second one, divide 5.08 by 2.54 to get total inches:
5.08 / 2.54 = 2 inches.
For the 3rd one, multiply 2.54 by 10 for total centimeters:
2.54 x 10 = 25.4 centimeters.
Note the first one given to you. 2.54 centimeters = 1 inches
The next one is 5.08 To solve, divide by 2.54:
5.08/2.54 = 2
2 inches is your answer
To solve the next one, 10 inch, multiply by 2.54
10 x 2.54 = 25.4
25.4 centimeters is your answer
hope this helps