Answer: d < -15
Explanation: When you're asked to solve an inequality like -7d < 105, your goal should be the same as it was when solving equations, to get <em>d</em> by itself on one side.
In this problem since <em>d</em> is being multiplied by -7 on the left side of the inequality, to get <em>d</em> by itself, we divide both sides by -7. But here is the rule you have to watch out for when solving inequalities.
When you divide both sides of an inequality by a negative number, you must switch the direction of the inequality sign.
So this greater than in our original problem becomes less than in our second step. On the left side, the -7's cancel and we are left with <em>d</em> and on the right side, 105 divided is -15. So we have <em>d < -15</em>.
Notice that I switched the direction of the inequality sign above.
