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2 Answers
May 16, 2018

20*13=260 economy class seats
20*5=100 business class seats

Explanation:

The ratio 13:5 describes the relationship between the economy and business class seats. First, add these numbers together to get 18. Now, 360/18=20, so we know there are 20 complete groups of seats. Therefore, each class of seats will be 20 times its respective number.
20*13=260 economy class seats
20*5=100 business class seats

260+100=360 Check
260/100=13/5 Check

May 16, 2018

There are 260 seats in economy class and 100 seats in business class.

Explanation:

Use two equations with two variables.

First, we know that the total number of seats on the plane is 360 seats.

Define variables:
"Let " B " be the number of business class seats, and "
"let " E " be the number of economy class seats"

color(blue)(E+B=360)

Our second equation is defined by rewording the second sentence of the problem. The problem basically states that the number of business class seats is 5/13 times the number of economy class seats. In equation form:

color(blue)(B = 5/13 * E)

Use substitution to solve for B and E - substitute the second equation into the first:

E + (frac{5}{13}*E) = 360

(18/13)*E =360

E = 360 * 13/18

color(green)(E = 260" seats in economy class")

More substitution:
B = 5/13 * (260)

color(green)(B = 100" seats in business class")