For once I agree with Marta Mossburg, that something needs to be done about Baltimore City public schools ("Baltimore City schoolchildren deserve a real choice," Sept. 12). But I'm very curious where she came up with the numbers she uses to push her idea for vouchers.

Unless she's living in a very different world from Baltimore, her numbers just don't add up. She says that Baltimore City spends $14,711 per student, which she says is the third highest in the nation. That may be true, but then she follows it up by saying, "Private school costs are lower than public school costs" and that a voucher system would cost only $42,00 per pupil over a three year period. Where in the world is she getting these numbers?

For this school year, the tuition at Gilman School is slightly over $22,000 per pupil, more than $7,000 more than what the City School system is spending. Boys Latin and St. Paul's are about the same, and Friends School is closer to $23,000 per pupil. Oldfields School and St. Timothy's School, which include room and board, are both over $45,000 per pupil, making them more than $30,000 more expensive per year than Baltimore City public schools.

So I'm puzzled. How in the world can Ms. Mossburg claim that private school is less expensive than public school? She must have Mitt Romney and Paul Ryan doing her math for her. And where does this "$4,200 per pupil over a three year period" number come from? If the state only gave vouchers worth that much to send a child to private school, that still leaves the parents responsible for picking up the remaining $62,000 — and that's if they choose the least expensive private schools. I fail to see how that's going to be any help at all.

Given the dismal picture Ms. Mossburg paints of academics in the Baltimore City public school system, and the shaky grasp of numbers she seems to demonstrate in her article, I can only reach one conclusion. Ms. Mossburg must have attended one of Baltimore's public schools.

William Smith, Baltimore