How many seats are there in each class?

Question

A plane has 360 total seats, which are divided into economy class and business class. For every 13 seats in economy class, there are 5 seats in business class. How many seats are there in each class?

Answer 1

Let b=number of seats in business class

Let e=number of seats in economy class

Given b+e=360 and e/13=b/5

multiply the second equation by 13:

13*e/13=13*b/5

e=13b/5

substitute for e in the first equation:

b+13b/5=360

multiply the above equation by 5:

5b+5*13b/5=5*360

5b+13b=1800

18b=1800

b=100

substitute for b in the first equation

100+e=360

100+e-100=360-100

e=260

b=100,e=260