Given that a/b = 3/4, b/c = 4/7
∴ a/c = a/b x b/c

Correct Option: D

Given that, a/b = 3/5, b/c = 4/7
∴ a/c = a/b x b/c = 3/5 x 4/7 = 12/ 35
&there4: a : c = 12 : 35

Given that 4a = 5b
∴ a/b = 5/4
Also 7b = 9c
∴ b/c = 9/7
∴ a : b = 5 : 4 = (5 x 9) : (4 x 9) = 45 : 36
and b : c = 9 : 7 = (9 x 4) : (7 x 4) = 36 : 28

Correct Option: A

Given that 4a = 5b
∴ a/b = 5/4
Also 7b = 9c
∴ b/c = 9/7
∴ a : b = 5 : 4 = (5 x 9) : (4 x 9) = 45 : 36
and b : c = 9 : 7 = (9 x 4) : (7 x 4) = 36 : 28
∴ a : b : c = 45 : 36 : 28

Let a/7 = b/9 = c/11 = K
Then a = 7K, b = 9K, c = 11K

Correct Option: C

Let a/7 = b/9 = c/11 = K
Then, a = 7K, b = 9K, c = 11K
∴ a : b : c = 7K : 9K : 11K = 7 : 9 : 11

Given that, 30 % of A = 20 % of B
⇒ A/B = 20/30 = 2/3

Correct Option: D

Given that, 30 % of A = 20 % of B
⇒ A/B = 20/30 = 2/3
⇒ A : B = 2 : 3

Given that, P : Q : R = 2 : 3 : 4
Let P = 2K, Q = 3K, R = 4K
∴ P/Q = 2K/3K = 2/3,
Q/R = 3K/4K = 3/4,
R/P = 4K/2K = 2/1

Correct Option: A

Given that, P : Q : R = 2 : 3 : 4
Let P = 2K, Q = 3K, R = 4K
∴ P/Q = 2K/3K = 2/3,
Q/R = 3K/4K = 3/4,
R/P = 4K/2K = 2/1
∴ P/Q : Q/R : R/P = 2/3 : 3/4 : 2/1
= (2 x 12)/3 : (3 x 12)/ 4 : (2 x 12)/1
= (2 x 4) : (3 x 3) : 24
= 8 : 9 : 24