Each classroom at HCS has a total of 26 desks. After Mr. Champagne ordered 75 new desks, the total number in the school was 543. How many classrooms does the school have?

Harry owes the bank money. to repay his debt, he paid $150 back to the bank each month. after 10 months, his remaining debt was $6900. what was the original amount of harry's debt? how long did it take harry to pay back his entire debt?