Equations with Two Variables

Question 1: Which of the following is a solution to the equation 3x-4y=1

Question 2: The output number or the variable in a function that depends upon another variable is the ________

Question 3: Grendel has $200 in a savings account. He plans to deposit $50 each week. If t is the total amount of money in the account after w weeks, which variable is the independent variable?