解:据题意,X+(X+1)+(X+2)+(X+3)+(X+4)=5X+10=45,解之得,X=7.
帮帮忙~! A*3=A (A 1) (A 2), X*5=X (X 1) (X 2) (X 3) (X 4) =5X 10 =45 5X=35 X=7