Step-by-step explanation:
If Aleah buys 2 DVDs for $6 and 2 CDs for $8 we can well assume that the DVDs are $3 dollars each and the CDs are 4 Dollars Each. If ling wants to buy 4 DVDs You would multiply how many DVDs she's buying with the price of the DVDs so (4x3=12) so Ling would have to pay $12 for the DVDs and $8 on the CDs
Pierre wants to spend $20 so with the previous information we can come to the solution that Pierre can buy 4 DVDs and 2 CDs for $20.