Răspuns:
4 si 1/2=(4·2+1)/2=9/2=4,5
4,5/3=0,5/x
4,5x=3·0,5=>x=1.5:4,5=>x=0,(3)=>x=3/9=>x=1/3
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(x+1)/(x+3)=4/5
5(x+1)=4(x+3)
5x+5=4x+12
5x-4x=12-5
x=7
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