Calculate Elasticity of demand in this example
Yes, the answer is -0.8.

Price Elasticity of Demand is defined as:
$$e_{\langle p \rangle} = \frac{\mathrm{d} Q/Q}{\mathrm{d} P/P}$$

You're given :
$$\mathrm{d} Q/Q = -0.08$$
and 
$$\mathrm{d} P/P = 0.1$$

ergo:
$$-0.08/0.1 = -0.8$$

I'm reasonably certain that by "Interpret your answer," your professor means that s/he wants you to explain what that number means, in layman's terms.

You can always check the Wikipedia entry.