a.I_____I
b.I_____I+15
c.I_____I+15+15
d.I_____I+15+15+15
Suma este 490 . Aflam suma partilor egale eliminand 15x6=90 .
490-90=400 ( suma partilor egale )
400:4=100 ( numarul a )
100+15=115 ( numarul b )
100+30=130 ( numarul c )
100+45=145 ( numarul d )
Verificare : 100+115+130+145=490