A cement mixture is composed of 3 elements. By weight, 1/5 of the mixture is sand, 3/4 of the mixture is water, and the remaining 6 pounds of the mixture is gravel. What is the weight of the entire mixture in pounds?  Choose the most appropriate option
A) 100	B) 120	C) 130	D) 140	E) 150

Rationale: "let the total weight be x . sand content = ( 1 / 5 ) x water content = ( 3 / 4 ) x gravel = x - ( 1 / 5 ) x - ( 3 / 4 ) x = ( 1 / 20 ) x = 6 x = 120 then answer will be b = 120"
Answer: B