What did reagan do to encourage economic growth? he implemented tax cuts. he supported deregulation of industries. he decreased defense spending. he balanced the budget.

Reagan implemented tax cuts 

Perhaps most famous of Reagan's economic policy is Reagan's emphasis on tax cuts, based on his administration's emphasis on "supply side economics" or what has commonly been called "trickle-down economics."  The idea was that if you provided tax cuts to those at the top running business, they would invest more in their business, hire more workers, pay better wages, etc.  Whether that's how it actually worked out is debated.

Reagan did also to some extent support deregulation of industries, but deregulation moves had begun before his administration and economists debate whether that was a high priority for the Reagan administration.