Determine the cash recepits for March based on the following information:
Cash payments $45500
April 1 cash balance $6750
April 30 cash balance $10000

Since the formula for determining your cash balance is:
Beginning Cash + Cash Receipts - Cash Payments = Ending Cash Balance

you just need to rearrange your formula so you can solve for your missing amount:

Ending Cash Balance - Beginning Cash Balance + Cash Payments = Cash Receipts