Do Not Pay Any Less, Mrs. Mess Puzzle Mrs Mess was buying a set of garden furniture.
The bill was seventy dollars.
She gave the attendant what she thought were
two $50 bills, (actually two $100 bills).
The attendant was sleepy and didn't notice either,
so he gave Mrs. Mess what he thought were
three $10 bills (actually three $50 bills).
Who ended up better off than they should?

not only in mathematics, scientific proof also are required in the other field of science. also maths proofs are of particular structure, containing steps and logics. so proving is like doing science, it is science. that's why it is important to prove. 

an inaccurate proof leads to errors, or stating results that are not accurate.  which wil mess the probelm up you dont want this

the answer is y = 11.54

hope this : )