multiple discount on total invoice
item qty price
x 1 500
y 2 500
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tot 1000
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discount 1(10%) 100 (1000*(10/100))
discount 2(5%) 45((1000-100)*(5/100))
discount 2(5%) 42.75((1000-100-45)*(5/100))
how in invoice i create these discounts ?