**URGENT**A store sells gift cards in preset amounts. You can purchase gift cards for $10 or ​$15. You have spent ​$340 on gift cards. Write an equation in standard form to represent this situation. What are three combinations of gift cards you could have​ purchased?Let x be the number of gift cards for ​$​10, and let y be the number of gift cards for ​$15. Write an equation in standard form to represent this situation.