Question

I have a doubt in maths like there is (7-r)(6-r)=12. so do I have to solve LHS or I can directly do (7-r)=12 , (6-r)=12 to find value of r, I ONLY WANT TO KNOW WHY WE HAVE TO SOLVE LHS FIRST!?
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Answer 1

Answer:

While CNG is comprised of methane, LPG is comprised of propane and butane. CNG is typically used as a substitute for gasoline in automobiles, while LPG is often used in the industrial, refrigeration, agricultural and catering industries.