Steps of adding 7+(-10) using number line are as following:
1) Draw a number line by ranging from -10 to +10.
2) Point out 7 on the number line.
3) Because -10 is added to 7 on the number line, please move 10 numbers left to 7 on the number line. We always go left in addition of a negative number on the number line.
4) The number we reach -3 on left side would be our final sum.
5) From the number we can clearly see that moving 10 number on left to 7, we get -3.
Note: We are moving left because of negative sign in front of 10.