The statement which is true in the choices is the third item in the choices such as "Nina makes 20x dollars at the clothing store each week". It was clearly stated in the given that x represent the total number of hours she worked in a week. This statement made the other items in the choices wrong.
so the way I did this was by adding how much he works per week which is 35 per week. so he works 70 hours in 2 weeks. he earns 10 dollars per hour. so 10 times 70 you get 700 but he spends 50. so 700 minus 50. you get 650. he has 650 dollars left.