Any naturally occurring, inorganic, crystalline substance with a fairly definite chemical composition is called a

City a and city b had two different temperatures on a particular day. on that day, four times the temperature of city a was 8â° c more than 3 times the temperature of city b. the temperature of city a minus twice the temperature of city b was â’3â° c. what was the temperature of city a and city b on that day? city a was 5â° c, and city b was 4â° c. city a was 3â° c, and city b was â’1â° c. city a was 8â° c, and city b was â’3â° c. city a was 5â° c, and city b was â’5â° c.

Can someone me with questions 15 to 17 plz.

Light waves can move through , but they travel fastest when they move through a(n) .