If twice the age of A is added to B’s age, the sum is 45 and if twic

1.	If twice the age of A is added to B’s age, the sum is 45 and if twice the age of B is added to A’s age, the sum is 30. Then the age of B is ……………… A) 20 B) 5 C) 10 D) 30
Answer» Correct option is (B) 5 Let age of A be x & age of B be y. Then according to first condition, we obtain 2x+y = 45 _______(1) According to second condition, we obtain x + 2y = 30 _______(2) Multiply equation (2) by 2, we get 2x + 4y = 60 _______(3) Subtract equation (1) from equation (3), we obtain (2x + 4y) - (2x + y) = 60 - 45 \(\Rightarrow\) 3y = 15 \(\Rightarrow\) y = \(\frac{15}3\) = 5 Hence, the age of B is 5. Correct option is B) 5

If twice the age of A is added to B’s age, the sum is 45 and if twice the age of B is added to A’s age, the sum is 30. Then the age of B is ……………… A) 20 B) 5 C) 10 D) 30

Answer»

Correct option is (B) 5

Let age of A be x & age of B be y.

Then according to first condition, we obtain

2x+y = 45 _______(1)

According to second condition, we obtain

x + 2y = 30 _______(2)

Multiply equation (2) by 2, we get

2x + 4y = 60 _______(3)

Subtract equation (1) from equation (3), we obtain

(2x + 4y) - (2x + y) = 60 - 45

\(\Rightarrow\) 3y = 15

\(\Rightarrow\) y = \(\frac{15}3\) = 5

Hence, the age of B is 5.

Correct option is B) 5