HELP DUE AT 12! I need to know

In triangle △abc, ∠abc=90°, bh is an altitude. find the missing lengths. ah=4 and hc=1, find bh.

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?

Zahra runs a 500-meter race at a constant speed. which graph shows her distance from the finish line during the race?