Let first number = P
And second number = Q
According to the question
P - Q = 10 ....(i)
And 3P - 4Q = 18...(ii)

on multiply eq (i) by 3 and then subtract eq (ii) from it
3P - 3Q = 54
3P - 4Q = 18
Q = 36

On putting the value of Q in the eq (i)
P = 18 + Q = 18 +36
⇒ P = 54

Correct Option: D

Let first number = P
And second number = Q
According to the question
P - Q = 10 ....(i)
And 3P - 4Q = 18...(ii)

on multiply eq (i) by 3 and then subtract eq (ii) from it
3P - 3Q = 54
3P - 4Q = 18
Q = 36

On putting the value of Q in the eq (i)
P = 18 + Q = 18 +36
⇒ P = 54
Required sum = P + Q = 54 +36 =90

Number of trees that can be planted on one side of road = (1760 / 20) + 1

Correct Option: D

Number of trees that can be planted on one side of road = (1760 / 20) + 1
= 88 + 1
=89

∴ Trees on the both side = 2 x 89=178

Let the third number = N
Then the first number = 3N
And second number = 3N/2
According to the question [N + 3N + 3N/2] / 3=154

Correct Option: C

Let the third number = N
Then the first number = 3N
And second number = 3N/2
According to the question [N + 3N + 3N/2] / 3=154
⇒ (2N +6N +3N) / 6 = 154
∴ N = (154 x 6) / 11 = 84
∴ Required difference = 3N - N = 2N
= 2 x 84 = 168

Let the number be P and Q
According to the question
(P + Q) = 2.5 (P - Q)
⇒ P + Q = 2.5P - 25Q
⇒ 3.5Q = 1.5P
⇒ P / Q = 7/3 .....(i)
Now PQ = 84

Correct Option: D

Let the number be P and Q
According to the question
(P + Q) = 2.5 (P - Q)
⇒ P + Q = 2.5P - 25Q
⇒ 3.5Q = 1.5P
⇒ P / Q = 7/3 .....(i)
Now PQ = 84
⇒ Q² = (84 x 3) / 7
⇒ Q² = 36
∴ Q = 6
&ther4; P = (7/3) x 6 = 14

Sum of the number = P + Q = 14 + 6 = 20

For even values of n, the number (10ⁿ - 1 ) consists of even numbers of nines and hence it will be divisible by 11.

Correct Option: C

For even values of n, the number (10ⁿ - 1 ) consists of even numbers of nines and hence it will be divisible by 11.