Subtract 25.
25 - 25 + x < -40 - 25
Simplify
x < -65
_____
An inequality is solved exactly the same way an equation is solved, with one exception.‡ Multiplying or dividing by a negative number reverses the sense of the inequality:
2 > 1
-2 < -1 . . . . multiplied by -1
___
‡ The exception can be generalized to the use of any function that reverses the ordering of its arguments. In Algebra, about the only function we use that has negative slope is the cosine function (and its inverse). You rarely see these used in inequalities.
