Tori works two jobs to pay for college. she tutors for $30 per hour and also works as a receptionist for $10 per hour. due to her class and study schedule, tori is only able to work up to 20 hours per week but must earn at least $200 per week. if t represents the number of hours tori tutors and r represents the number of hours she works as a receptionist, which system of inequalities represents this scenario?

a t + r greater than or equal to 20
30t + 10r = 200
b t + r less than or equal to 20
30t + 10r less than or equal to 200
c t + r less than or equal to 20
30t + 10r = 200
d t + r less than or equal to 20
30t + 10r greater than or equal to 200