Answer
There is no interval for which the product will at least break even.
Work Step by Step
$$60x\geq 70x+500$$
Move $70x$ to the left and change sign:
$$60x-70x\geq 500$$
$$-10x\geq 500$$
Divide both sides by $-10$ and reverse the inequality sign:
$$x\leq\frac{500}{-10}$$
$$x\leq-50$$
$x$ cannot be negative. So, there is no solution.
