Răspuns:
12.
A*56/90=35/27
A=35/27:56/90
A=35/27*90/56
A=25/12
13.
21/220:A =5*5/42
21/220:A=215/42
A=21/220:215/42
A=21/220*42/215
A=441/4730
A este fractia
sper ca intelegi! bafta!
