Question

-15 < a + 3 + 8a < 12

Answer 1

`-2 < a < 1`

Explanation:

-15 < 9a + 3 < 12 (Combine like terms)

-18 < 9a < 9 (Subtraction Property)

-2 < a < 1 (Division Property)

Note that just like solving a linear equation, instead of having two sides, you have three. And, whatever you carry out on one side, you have to carry out on all three.

Although, unlike linear equations, if you are dividing/multiplying all sides with a negative integer, then you have to flip the signs.