How do i know if a function is one-to-one?

2y= 3 2 x−2 y = − 1 3 x + 1 y=− 3 1 x+1

Clara schumann is buying bagels for her coworkers, she buys a dozen bagels priced at $5.49 a dozen. the bakery's cost for making the bagels is $2.25 per dozen. what is the markup rate based on selling price on a dozen bagels?

Polygon hh is a scaled copy of polygon gg using a scale factor of 1/4. polygon h's area is what fraction of polygon g's area?