51. I checked the comments but I still didn't understand it, sorry :/
54.
(43+45+47+49)=184
They are all odd and they are in consecutive order (one after another)
The answer would be 340 and its correct because I did it!!
Answer: 60 percent decrease
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Change in price = new - old = 100 - 250 = -150
The negative change means the price has gone down
Divide this change in price over the original 250 and convert to percent form
(change in price)/(original price) = -150/250 = -0.60
which converts to -60%
The negative percent change in price indicates a price decrease
So the price goes down by 60% meaning that it lost 60% of its value
Note how 60% of 250 is 0.60*250 = 150 which was the change in price computed earlier.