Kate and Mario are saving money for a vacation. This graph shows the money in their bank accounts. • Kate started out with $425 in her account and works at a job paying $10 per hour. k(t) = 10t + 425 O Mario started out with $350 in his account and works at a job paying $12.50 per hour. m(t) = 12.5t + 350 Let s(t) be the total amount of money they've saved combined. What is the equation for s(t)?​