Hi guys,
I'm totally useless at maths and my brain is really playing up. Could someone skim through my calculations and see if it all makes sence.

I'm selling a product called a 'KD' which costs my (the retailer) £4.30. The price that it's sold to customers varies.

Sale price | Cost (KD cost and in some cases postage).
£7.00 – (£4.30)= £2.70 for selling 1
£60.00 – (£5.32+[£4.30x5=£21.50]) = (£60.00 – £26.82) = £33.18 for selling 5
£11.00 – £1.60 = £9.40 for selling 1

Profit for selling 7 so far (5+1+1) so far: (2.70+33.18+9.40)= £45.28

£45.28 is profit I made by selling 7KD's ontop of paying back the amount it cost me to buy them?

Yes, your computation is correct.

Only, in the last sale of 1 KD, why is it that your cost is only 1.60 pounds? What happened to the 4.30 pounds per KD?

That was sold for £11, £1.60 was the cost. Also, am I ring in assuming that I've made back my investment (£43 total for 10 KD's) + made an extra £45.8 (so far)?

Also let's say if at the end I've sold all 10 and made £70. Everytime if I sell and make the same amount it will always be - £43 investment returns back £70 + initial investment.

I still don't get it why your cost was only 1.60 pounds when you bougth the KD for 4.30 pounds.

Yes, you got back your 43 pounds investment and you made a profit of 45.80 pounds, according to your computations.

If you "profited" 70 pounds from 10 KD's one time, it will always be like that?
Yes, if the same conditions remain the same.
No, if you have to sell at different prices due discounts, etc.

Ah, I understand what you are saying now. So it would be:

Sale price | Cost (KD cost and in some cases postage).
£7.00 – (£4.30)= £2.70 for selling 1
£60.00 – (£5.32+[£4.30x5=£21.50]) = (£60.00 – £26.82) = £33.18 for selling 5
£11.00 – (£1.60+£4.30) = £5.10 for selling 1

Profit for selling 7 so far (5+1+1) so far: (2.70+33.18+5.10)= £40.98

:P Thanks

Now that's okay.

Don't mention it.