解：设这个数为x，则 80%x-10×3/8=1又3/4 80%x-15/4 =7/4 解得x =0.4
设这个数为x，80%x-10X3/8=7/4 解得x=6.875
设它为x80％x-10×3/8=7/4 80％x=15/4＋7/4 80％x=22/4 x=55/8
