Question

现有1角.5角.1元硬币各10枚,从中抽取15枚,共职7元.1角.5角.1元硬币各取多少枚?

Answer 1

设1角(0.1元),5角(0.5元),1元各取了x,y,z枚,则

x+y+z=15(1)

0.1x+0.5y+z=7(2)

x=15-y-z

x+5y+10z=70

15-y-z+5y+10z=70

4y+9z=55(3)

9z