On an airplane, there are two seats on the left side in each row and three seats on the right side. There are 27 seats on the right side of the plane.

60

Step-by-step explanation:

n = number of rows

Since we know the airplane has an equal number of rows on the right side as it does on the left side, then we can mathematically show that:

number of sears on the right side = 3n = 90 seats

number of sears on the left side = 2n = ? seats

3n = 90

n = number of rows = 90/3 = 30 rows

so:

2n = 2 (30) = 60 seats on the left side