求解答，拜托大神，求详细解答步骤

（X1B+X2B+X3B+X4B+X5B+X6B+X7B+X8B+X9B）= RXB( X1+X2+X3+X4+X5+X6+X7+X8+X9 ) = RXB = RX/( X1+X2+X3+X4+X5+X6+X7+X8+X9 )= 90.19/( 95.20 + 95 + 115 + 116 + 115 + 65 + 73 + 65 + 65)=0.11215 。