-2 times three sevenths

1. what are the missing reasons in the proof 2. it's in the second picture and 3

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?

The length of the shadow of a building is 120 meters, as shown below: building shadow 120 m what is the height of the building? (1 point)