* The type of school: Free, publicly funded schools were extremely rare in 1750, especially in what are now the United States and most of Europe. Most schools were private, church-run (often with fees), or charity schools (for the poor, often with fees, though potentially lower ones or even free depending on circumstances).
* The location: Schooling varied dramatically by region and country. Some areas had more established systems, even if still largely private, than others.
* The family's socio-economic status: Wealthier families could and did pay for private tutors or to send their children to better-resourced private schools. Poorer families often relied on charity schools (if available) or had their children work.
In short, there was no universal answer. Most children did not attend school at all in 1750, and those who did often had to pay, or their families did, to access education. Free education was the exception, not the rule.