a) 2x(cu linie, o sa notez cu steluta *)=20 +x
xx*=10x+x
2x*+xx*=20+x+10x+x=20+12x
20+12x=104
12x=104-20
12x=84
x=84:12
x=7
b) 51x*=500+10+x
5x1*=500+10x+1
x51=100x+50+1
51x*+5x1*+x51*=1395
500+10+x+500+10x+1+100x+50+1=1395
1062+111x=1395
111x=1395-1062
111x=333
x=333:111
x=3