Answer:
x < -2 (No, he shouldn't have reversed the inequality symbol).
Step-by-step explanation:
Given the algebraic expression;
19 - 2(1 - x) < 13
Opening up the bracket, we have;
19 + (-2*1) + (-2*-x) < 13
19 + (-2) + (2x) < 13
19 - 2 + 2x < 13
17 + 2x < 13
Rearranging the equation, we have;
2x < 13 - 17
2x < -4
Dividing both sides by 2, we have;
<em>x < -2</em>
Hence, your friend shouldn't have reversed the inequality symbol (sign).
Note: you should only flip the inequality symbol (sign) when you're dividing by a negative number such as -2.
For example, if we had re-arranged the equation as;
17 - 13 < -2x
4 < -2x
Dividing both sides by -2, we have;
4 > x
