I see your current weight is 10st12lb
Convert it into lbs only. 14lbs to the stone.
So, 10st = 140lbs, then add the odd 12lbs.
So your current weight in lbs is 152lbs
10% of 152lbs is 15.2lbs. I would round it up to the nearest half pound.
Take 15 and a half pounds from your current weight of 152lbs gives you
136.5lbs.
Convert this back into stones by dividing it by 14
This I think would be 9st7.5 lbs.
This is only an example, you would need to do it from your starting weight