Value of a margin call : possible error

You purchase 500 shares at $170.30 per share. You borrow $51 090 from your broker to help finance the transaction. The interest rate on the loan is 3% for the month.

I know the initial margin by calculation is 40%.

The question I have is what is the value of the margin call if the price falls to $150 and the maintenance margin is 35%?

the answer says $2340.

How did they get that?

The original value of your equity is:

40% × $170.30 × 500 = $34,060

When the price drops to $150/share, your loss is:

($170.30 − $150.00) × 500 = $10,150

leaving you with equity of:

$34,060 − $10,150 = $23,910

Your required maintenance margin is:

35% × $150.00 × 500 = $26,250

Thus, you’re short by:

$26,250 − $23,910 = $2,340

Why don’t you also factor in the interest on the borrowed funds?

Did it take a month for the price to fall to $150?