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2014-10-28T17:04:30+02:00
a+b = 45
ac+bc =450⇒c(a+b)=450⇒c·45=450⇒c=450:45⇒c=10


a)( a+b)-c=45-10=35
b)(a+b)+2c=45+2·10=45+20=65
c)3a+3b+4c
=3(a+b)+4c=3·45+4·10=135+40=175