An "adding" PASTE and a CELL update

Hi

I need 2 macros:

1. An ordinary macro that would copy values only of G7:G29 pasting them to H7:H29 BUT adding the G value to the H value.
For example, H11 would become 223.74.

2. An automatic sheet changing macro that when a value (numeric) is entered in J7:J29, that value would be subtracted from either the value in H or I, same row, which ever is filled, and the value in H or I would be updated.
(H and I will NEVER have values on the SAME row).
The value entered in J cannot be greater than the value entered in H or I.