Answers

2014-06-06T20:05:25+05:30
Let the cms tree grows each year be x
height of tree after 7 years = 7x+90
height of tree after 6 years = 6x+90
therefore 7x+90 = 9(6x+90)
i.e. 7x+90 = 54x+810
i.e. 54x-7x = 810-90
i.e. 47x = 720
i.e. x = 15.3
at the end of 12 years height = 90+12*15.3 = 273.6
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