OG11上的一道数学题, 看解释都不懂,大家讨论一下吧

Of the three-digit integers greater than 700, how many have two digits that are equal to each other and the remaining digit different from the other two??

key is 80.

confusing, .. 大家讨论一下吧.

same                  701-799     800-899     900-999

tens and ones             8          9           9

hundreds and tens         9          9           9

hundreds and ones         9          9           9

答案中给出如上图表做解释, 但是我觉得是忽略了百位为零的情况, 大家觉得呢?

犯晕了. 已经明白了.THANKS.