Jay Pembroke started a business. During the first month (April 20--), the following transactions occurred.

Invested cash in business, $18,428.
Bought office supplies for $4,433: $1,896 in cash and $2,537 on account.
Paid one-year insurance premium, $1,003.
Earned revenues totaling $3,402: $1,302 in cash and $2,100 on account.
Paid cash on account to the company that supplied the office supplies in transaction (b), $2,198.
Paid office rent for the month, $603.
Withdrew cash for personal use, $109.

To determine the ending cash balance for Jay Pembroke's business at the end of the first month, we need to analyze the transactions and calculate the net effect on cash. Let's break down each transaction:

1. Invested cash in business, $18,428:
This transaction increases the cash balance by $18,428.

2. Bought office supplies for $4,433: $1,896 in cash and $2,537 on account:
This transaction reduces the cash balance by $1,896.

3. Paid one-year insurance premium, $1,003:
This transaction reduces the cash balance by $1,003.

4. Earned revenues totaling $3,402: $1,302 in cash and $2,100 on account:
This transaction increases the cash balance by $1,302.

5. Paid cash on account to the company that supplied the office supplies in transaction (b), $2,198:
This transaction reduces the cash balance by $2,198.

6. Paid office rent for the month, $603:
This transaction reduces the cash balance by $603.

7. Withdrew cash for personal use, $109:
This transaction reduces the cash balance by $109.

To calculate the ending cash balance, we add up all the changes to the cash balance:

Starting cash balance: $0
+ $18,428 (investment)
- $1,896 (office supplies purchase in cash)
- $1,003 (insurance premium payment)
+ $1,302 (revenue received in cash)
- $2,198 (payment of accounts payable)
- $603 (office rent payment)
- $109 (cash withdrawal for personal use)

Total ending cash balance = $18,930

Therefore, the ending cash balance for Jay Pembroke's business at the end of the first month is $18,930.