43×99+43=4257+43=43003/5 ➗ [(1/5+1/3)➗2/9]=3/5➗[8/15➗2/9]=3/5➗[8/15×9/2]=3/5➗12/5=3/5×5/12=1/4 (PS 分子在“/”前面,后面除号变乘号所以分子分母位置颠倒)4/9×(3/10➗3/5+2/5)=4/9×(1/2+2/5)=4/9×9/10=2/5