请帮忙数学题

liutao1979

If k is posivie three-digit integer,what is the hundreds digit of k?

1 the hundreds digit of k+150 is 4

2 the tens digit of k+25 is 7

答案是e，帮忙解答

germaineilya

let k be abc, the question ask for a

1 abc

  150

----------

  4de

so  it can be that a+1=4, a=3

or b+5>10, a+1=3, a=2

insufficient

2   abc

     25

---------

    x7y

dosent tell us anything about a

insufficient

1+2: 2 dosent tell us if b>5, cos c+5might be greater than 10, so b could be 4 or 5

therefore e

liutao1979

thanking you very much