In january, a bookstore sells 450 books, but in february, it sells only 300 books. what is the percent of change from january to february?

Each month, a shopkeeper spends 5x + 14 dollars on rent and electricity. if he spends 3x−5 dollars on rent, how much does he spend on electricity? for which value(s) of x is the amount the shopkeeper spends on electricity less than $100? explain how you found the value(s).

Find the quotient with the restriction.

Cody was 165cm tall on the first day of school this year, which was 10% taller than he was on the first day of school last year.