If 4a = 5b = 30, then 40ab =
Choose the correct answer:
A) 900
B) 1800
C) 2250
D) 1650
E) 1250

Rationale: "4 a * 5 b = 30 * 30 = 900 20 ab = 900 i . e . 30 ab = 1800 answer : option b"
Answer: B