How to count lines within polygons?

Question

I would like to count the amount of lines within polygons.

The questions I would like to answer are: How many lines are within each polygon (enveloped AND intersecting)? How long is each line within each polygon OR how long are all the lines (combined) within each polygon?

I am using QGIS 2.18.12 (do not know how to write code)

Answer 1

first calculate all lines lenght,

second use Select By Location proccess (intersect etc.),

last one is Statistics By Categories proccess.