Question

Two student appeared for an examination. One of them secured 21 marks more than the other and his marks answers with explanation were 80% of the sum of their marks. The marks obtained by them are

Answer 1

Answer:

The marks obtained by the students is 21 and 7.

Step-by-step explanation:

Let the students marks be a and b respectively.

Let a be the student with higher marks.

∴ a - b = 21     ...Equation (i)

a = 80% of (a+b)

⇒ a = 0.8 (a + b)

⇒ a = 0.8a + 0.8b

⇒ (1 - 0.8)a - 0.8b = 0

⇒ 0.2a - 0.8b = 0

⇒ 2a - 8b = 0  .... Equation (ii)

Multiplying eq (i) with 8 and subtracting eq (ii) from it

(8-2)a - (8-8)b = 168

⇒ 6a = 168

⇒ a = 28

Substituting a in equation (i)

b = a - 21 = 28 - 21

⇒ b = 7