Answer:

Step-by-step explanation:
Given △KMN, ABCD is a square where KN=a, MP⊥KN, MP=h.
we have to find the length of AB.
Let the side of square i.e AB is x units.
As ADCB is a square ⇒ ∠CDN=90°⇒∠CDP=90°
⇒ CP||MP||AB
In ΔMNP and ΔCND
∠NCD=∠NMP (∵ corresponding angles)
∠NDC=∠NPM (∵ corresponding angles)
By AA similarity rule, ΔMNP~ΔCND
Also, ΔKAP~ΔKPM by similarity rule as above.
Hence, corresponding sides are in proportion



Adding above two, we get

⇒ 
⇒ 
⇒ 
⇒ 
⇒ 
⇒ 
2 3/8 / 1 1/4
= 19/8 / 5/4
=19/8 * 4/5
= 19/10
answer is B 19/10
7/10 ÷ 1/5 = 3 1/2 because if you just find the reciprocal of the second number (in this case 1/5) and then simply multiply the two numbers straight across after you find the reciprocal, you will need to convert and simplify as needed, and then you get your answer.