On an airplane, there are two seats on the left side in each row and three seats on the right side. there are 150 seats altogether. how many seats are on the left side of the plane and how many are on the right?

All together, there are 5 rows. 150 divided by 5 is 30, so each row has 30 seats. 
to make that a bit more visual for you, here: 

(each 30 is a row and the underscore is the isle)
30 30 30___30 30

30 x 3 = 90
30 x 2 = 60

There are 90 seats on the left and 60 on the right. 

It is 5.8 you add all of the up to equat 180 then solve the equation