Last month, Hector launched an online shop that sells T-shirts with his original designs. He sold 15 shirts last month and 18 shirts this month. Hector has been advertising his shop on social media and thinks his sales will continue to grow. Write an exponential equation in the form y=a(b)x that can model Hector's monthly shirt sales, y, x months after opening his shop. Use whole numbers, decimals, or simplified fractions for the values of a and b. y = After how many months will Hector's monthly sales exceed 50 shirts? months