Among four cars, weight of C1 is twice the weight of C2. Weight of C3 is half of the weight of C2. C4 is 40 kg heavier than C2, but 40 kg lighter thanC1. What is the weight (in kg) of C4?
Product of digits of a 2-digit number is 18. If we add 63 to the number, the new number obtained is a number formed by interchange of the digits. Find the number.