Problem $1$: Cash collection schedule

ZMart Inc. estimates that $20\%$ of its monthly sales are to cash customers, while the remaining sales are to credit customers.

Of the credit customers, $30\%$ pay their accounts in the month of sale, while the remaining $70\%$ pay their accounts in the month following the month of sale.

Projected sales for the next three months are as follows:

$\backslash$table$[[$Total sales,October,November,December$],[$Total sales,$$150,000,$$$180,000,$$$210,000$