What is the change in elevation between 8,500 m to 3,400 m?

Landon wrote that 3−2.6=4. which statement about his answer is true?

Sam opened a money-market account that pays 3% simple interest. he started the account with $7,000 and made no further deposits. when he closed the account, he had earned $420 in interest. how long did he keep his account open?

What is the benefit of converting measures in a ratio to the same unit