On one flight, the airline sold twice as many economy class tickets as business class tickets. Economy class costs $400 and business class costs $900. Five of the economy class ticket holders redeemed a voucher and did not have to pay. The total revenue of the flight was $49 000.
a) Solve the equation 900n+400(2n-5)=49000 for n, the number of business class travellers
b) How many travelled economy class?

Question

On one flight, the airline sold twice as many economy class tickets as business class tickets. Economy class costs $400 and business class costs $900. Five of the economy class ticket holders redeemed a voucher and did not have to pay. The total revenue of the flight was $49 000.
a) Solve the equation 900n+400(2n-5)=49000 for n, the number of business class travellers 
b) How many travelled economy class?