Hi Janet,

There are 90 two digit numbers 10, 11, 12, ... 99.

1) How many of them have the digit 7 in the units position?

These are 17, 27, ... 97

2) How many of them have the digit 7 in the tens position?

These are 70, 71, 72, ... , 79

Add the answers you got to questions 1 and 2. This isn't the correct answer because you have included the number 77 in 1 and 2 and you should only count it once. Thus the correct answer is

(the answer to 1) plus (the answer to 2) minus 1

I hope this helps,
Penny