是这个吧6.3*8.7+8.7*3.
6.3*8.7+8.7*3.7
=(6.3+3.7)*8.7
=10*8.7
=876.3+8.7，不是乘6.3+8.7+8.7*3.7=6.3+8.7*4.7=6.3+40.89=47.19