Given:

Cost price: R10

Profit rate: 20%

The selling price is then the cost price increased by 20% of the cost price.

Selling price = Cost price+Profit rate*Cost price.

PSK=R10+20%*R10 =R10+0.20*R10 =1.20*R10 =R12ZSK

Thus the selling price is R12.

Cost price: R10

Profit rate: 20%

The selling price is then the cost price increased by 20% of the cost price.

Selling price = Cost price+Profit rate*Cost price.

PSK=R10+20%*R10 =R10+0.20*R10 =1.20*R10 =R12ZSK

Thus the selling price is R12.