economic question 22

Last week at a Price of 2.8 the Quantity of some product sold was 28.8. This week at a Price of 15.1 the Quantity sold is 16.3. These two price/quantity combinations are points on the demand curve. What is the price elasticity of demand?

Remember the answer should be a negative number and round to the nearest 0.01.

I need the answer for the question above