Answer
See below.
Work Step by Step
Let $x$ be the selling price, then $900000\leq x\leq1100000$. Then the commision ($y$) is:
$45000+(x-900000)\cdot0.25$. Since $900000\leq x\leq1100000$, the commision is:
$45000+(900000-900000)\cdot0.25\leq y\leq45000+(1100000-900000)\cdot0.25\\45000+0\cdot0.25\leq y\leq45000+200000\cdot0.25\\45000\leq y\leq95000$
The percentage varies between $\frac{45000}{900000}=5\%$ and $\frac{95000}{1100000}=8.6\%$
