Fie A,B, C, D, masurilecelor 4 unghiuri ale patrulaterului convex atunci A/3=B/4=C/5=D/6=(A+B+C+D)/(3+4+5+6)=360°/18=20° A=3*20°=60° B=4*20°=80° C=5*20°=100° D=6*20°=120° as simple as that!!