Question

solve the equation: -13<3d+2<11

Answer 1

$-13 < 3d+2 < 11\ \ \ \ |subtract\ 2\ from\ both\ sides\\\\-15 < 3d <9\ \ \ \ \ |divide\ both\ sides\ by\ 3\\\\-5 < d < 3\Rightarrow d\in(-5;\ 3)$

Answer 2

-13 < 3d + 2 < 11
  -2           -2    -2
  -15 < 3d < 9
    3       3     3
    -5 < d   < 3
           d ∈ (-5, 3)