 
<translate> Wani shago yana ba da rangwame a kan alkalami. Idan ka sayi alkalami 10 a farashi na yau da kullum, za ka iya samun 10 na gaba don rabi. Wani abokin ciniki ya shigo ya sayi alkalami 20 a kan dala 30. Menene farashin al'ada na alkalami guda a cikin dala? Bari mu yi tunani da farko. Sarkar tunani: <eng> A shop is offering a discount on pens. If you buy 10 pens at the regular price, you can get the next 10 for half off. A customer came in and bought 20 pens for $30. What's the regular price of one pen in dollars? Let's think first. Chain of thought: 