Let us assume the ten's digit of the number is n. Then the unit's digit will be 3n.
According to question,
The sum of the digits is equal to 8.
sum of the digit = 8
⇒ n + 3n = 8
Solve the equation.

Correct Option: B

Let us assume the ten's digit of the number is n. Then the unit's digit will be 3n.
According to question,
The sum of the digits is equal to 8.
sum of the digit = 8
n + 3n = 8
⇒ 4n = 8
⇒ n = 2
So, ten's digit is 2 and unit's digit is 6.
So the number = 10n + 3n = 10 x 2 + 3 x 2 = 20 + 6 = 26.

Let us assume the ten's place digit be x.
Then, the number = 10x + 3
and sum of digits = x + 3
According to question,
So, ( x + 3 ) = 1/7( 10x + 3 )
Solve the equation.

Correct Option: C

Let us assume the ten's place digit be x.
Then, the number = 10x + 3
and sum of digits = x + 3
According to question,
So, ( x + 3 ) = 1/7( 10x + 3 )
⇔7x + 21 =10x +3
⇔ 3x = 18
⇔ x = 6
The number = 10x + 3 = 10 x 6 + 3 = 60 + 3 = 63

Let us assume the number be N.
According to question,
A number when subtracted by 1/7 of itself gives the same value as the sum of all the angles of a triangle,
N - N x 1/7 = 180 ( As we know sum of all angels of a triangle is 180 .)
Solve the equation.

Correct Option: B

Let us assume the number be N.
According to question,
A number when subtracted by 1/7 of itself gives the same value as the sum of all the angles of a triangle,
N - N x 1/7 = 180 ( As we know sum of all angels of a triangle is 180 .)
⇒ N - N/7 = 180
⇒ (7N - N)/7 = 180
⇒ (7N - N) = 180 x 7
⇒ 6N = 180 x 7
⇒ N = 180 x 7/6
⇒ N = 30 x 7
⇒ N = 210

Suppose the number of cows = a therefore , the number of herdsmen = a
The total number of legs = Legs of cows + Legs of herdsmen ( Cow has 4 legs and herdsmen has 2 legs )
The total number of legs = a x 4 + a x 2 = 4a + 2a = 6a
The total number of heads = Heads of cows + Heads of herdsmen ( Cow has 1 head and herdsmen has also 1 head )
The total number of heads = a + a = 2a
According to question,
The total number of legs was 28 less than four times the number of heads,
Solve the equation.

Correct Option: D

Suppose the number of cows = a therefore , the number of herdsmen = a
The total number of legs = Legs of cows + Legs of herdsmen ( Cow has 4 legs and herdsmen has 2 legs )
The total number of legs = a x 4 + a x 2 = 4a + 2a = 6a
The total number of heads = Heads of cows + Heads of herdsmen ( Cow has 1 head and herdsmen has also 1 head )
The total number of heads = a + a = 2a
According to question,
The total number of legs was 28 less than four times the number of heads,
6a = 4 x 2a - 28
⇒ 8a - 28 = 6a
⇒ 8a - 6a = 28
∴ a = 28/2 = 14

Let the ten's digits be x and unit's digit be y.
Then,(10x + y) - (10y + x)=36 ⇔9(x-y)=36
⇔ x - y=4

Correct Option: B

Let the ten's digits be x and unit's digit be y.
Then,(10x + y) - (10y + x)=36 ⇔9(x-y)=36
⇔ x - y=4