e)175:x=345:43
3,4:x=6,8:43
3,4:x=5,1
x=3,4:5,1
x=23
f)x:45 =258:54
x:45=52
x=52×45
x=2
g)(x×0,25+2012)×2013=(50+2012)×2013g)
(x×0,25+2012)×2013=2062×2013
x×0,25+2012=(2062×2013):2013
x×0,25+2012=2062
x×0,25=2062−2012
x×0,25=50
x=50:0,25
x=200
h)(x−12)×53=74−12h)
(x−12)×53=54
x−12=54:53
x−12=34
x=34+12
x=54
e: =>17/5:x=51/10
hay x=2/3
f: =>x:4/5=5/2
=>x=5/2x4/5=2
g: =>0,25x+2012=50+2012
=>0,25x=50
hay x=200