Joaquim has new babies at home, so he cares only about diapers and wipes. Joaquim's preferences are represented by written, where D is the number of(,)=^2diapers and W is the number of wipes that Joaquim purchases.

Suppose the price of diapers per pack is $30 and the price of wipes per pack is $10. If Joaquim's weekly budget is $900. What is the solution to Joaquim's utility maximization problem (you can directly use the equal-marginal principle to solve it)? How many diaper and wipe packs would Joaquim weekly buy?