complicated re-calculation price and total for stock and customer when price decrease

Hi experts ,
I hope to find help for this project .
the result will be in STOCK sheet for columns E,F and CUSTOMER sheet under name is already existed as highlighted .
so should match column B between sheets LOWER & STOCK and search for the matched item then will subtract column G for LOWER sheet from column F for STOCK sheet and divide values in column F / values in column D to show values in column E as highlighted in RESULT stock . as to CUSTOMER sheet will copy values from cells C6,E7,G6 and the TOTAL value should put in column E based on matching name cell E7 with column B for CUSTOMER sheet and put under into lastrow for the same name as I did it by highlight in RESULT CUSTOMER .
with considering about TOTAL value in LOWER sheet will change in location based on how item I need add it before SUBTOTAL row.

awesome !
could you add formula in column F for CUSTOMER sheet when add under name instead of value?
because the values precede it contains formula

Well, just I wanted to make the things more formatting .
Thanks so much for your assistance.