When solved (x + 1 < 4) ∩ (x - 8 > -7) becomes: (x+1-1 < 4-1) ∩ (x - 8 +8 > -7+8 ) (x < 3) ∩ (x > 1). and if you change places it will become even more obvious: ( 1<x ) ∩ ( x < 3 ) meaning: x is set of all numbers greater than 1 and less than 3 or otherwise: {x | 1 < x < 3}
