How to limit the figure?
Initial:

When I input 60 in Field A and 80 in field B. Nothing is appeared when the total amount is smaller than 100

When I input 60 in Field A and 80 in field B. Alert is appeared when the total amount is greater than 100.

Alert is appeared when the total amount is greater than 100. The Alert message is "the total amount cannot be exceed 100"
How to make relevant javascript code for this activity?? Thank you.
