F7 exam june

Hi My dear Tutor, I thought increase in opening inventory 300 and increase in closing inventory 450 and think I made a mistake.

I just produced example by myself in order to observe figures how change if i increase both opening and closing inventory.

From my point of view,
my own made example
opening inventory 500
purchase 600
closing (500)
cost of sales-600

let us increase opening and closing inventory by 300 and 450 respectively

opening inventory 500+300=800
purchase-600
closing inventory (500+450)-950
cost of sales 450

cost of sales decreased to 450 how i need to increase cost of sales to 600 i have to add 450 over cost of sales in trial balance simultaneously deduct 300 which will give 600.

From this conclusion I made mistake not to deduct 300 from cost of sales because i just added 450 over cost of sales.The rest my calculation is correct.

Anyway I am disappointed when i made such mistake.

This is what I have been thinking.