The correct answer is 60 seats on the left side, but you might also want to know how I got that answer . . .
Let's say, 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
Thus:
2n = 2(30) = 60 seats on the left side
as for how many seats all together, just add . . 90 + 60 = 150 seats total
