Subject :IMO Class : Class 9

** Arpan cut a cake in two equal parts and one of these two pieces is again cut into
equal parts. Each small part is of 20 grams. If there are seven parts of the whole cake,
what was the weight of the original cake ?**

(A) 140 grams

(B) 280 grams

(C) 240 grams

(D) 300 grams

Please explain