Grammar Tips: feedback: https://grammarhow.com/feedbacks/ very good vs very well: https://grammar.yourdictionary.com/grammar-rules-and-tips/when-to-use-good-and-when-to-use-well.html year old vs years old: https://www.espressoenglish.net/common-errors-in-english-year-old-or-years-old/
Solving practical problems with mathematics