Найдите подходящее число, на которое можно разделить обе части уравнения и найти решение уравнения 3x = 12 | :
x =

5x = –10 | :
x =

–7x = 21 | :
x =

0,1x = 2 | :
x =

0,01x = –4 | :
x =

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?