How do you write 15,409 in expanded form

All per-unit concepts rely on ratios, meaning, to provide a type of measurement

What set does not contain -3 the set of all real numbers the set of all integers the set of all whole numbers the set of all rational numbers

Two cyclists 84 miles apart start riding toward each other at the same. one cycles 2 times as fast as the other. if they meet 4 hours later, what is the speed (in mi/h) of the faster cyclist?