Heidi must divide 870 bales of hay between three stables so that the second has 90 bales more than the first, but 150 less than the third

Let the number of bales in the second stable be represented by x. The number of bales in the first stable is equal to x - 90, and the number of bales in the third stable is x + 150. The three stables together equal 870 bales. This gives the following equation:
 (x) + (x - 90) + (x + 150) = 870
 which can be rewritten to combine terms as
 3x - 90 + 150 = 870
 or
 3x + 60 = 870.
 Subtracting 60 from both sides gives us:
 3x = 810.
 Divide both sides by 3 to solve for x: x = 270.
 Thus, the second stable will have 270 bales of hay in it. The first stable will have that number minus 90, or 180 bales of hay in it. The third stable will have 270 plus 150, or 420 bales of hay in it.