Write the Slope Intercept Form equation of the line that passes through the points (-4,-2) and (-2,3)

Solve for x i'll try to attach the files bc it's not letting me for some reason

How do you solving the solution of each system using elimination?

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?