Free cash flow

Dillin Inc. reported the following on the company's statement of cash flows in $20Y2$ and $20$Y$1$:

Eighty percent of the net cash flow used for investing activities was used for the purchase of property, plant, and equipment.

a$.$ Determine Dillin's free cash flow for both years.

b$.$ Has Dillin's free cash flow improved or declined from $20Y1$ to $20$ Y$2?$