a) (11/10+x/10)+(22/10+2x/10)+(33/10+3x/10)+(44/10+4x/10)=61
Inmultim cu 10 ca sa scapam de numitor si:
11+x+22+2x+33+3x+44+4x=61
6x+110=61
6x=-49
x=-49/6
b) x+2x+3x+....+50x-1234/10=37016/10
x(6x+50x:2)-1234=37016
6x²+25x²=38250
31x²=38250
x=1233
c) 575/100+5/10*8+3x/10=1605/100
Amplificam cu 10 pe 3x/10 si 5/10 si ne da
575/100+50/100*8+30x/100=1605/100
Amplificam toata relatia cu 100 sa scapam de numitor
575+400+30x=1605
975+30x=1605
30x=630
x=21