1st tint 65% so left 35% not rejected..
so out of 35% not rejected, 82% will be rejected by second tint.
so after all that the not rejected rate should be around 7%

not sure but i do think it is safe to think like that..
logically thinking that is

but ur example got some flaw..
sand is a thing with weight and shape etc while light/heat is a form of energy..
tint film limit/reject, not filter the heat..
im not sure but what i mean is if u flow 1 litre of water from a pipe, the x(can be anything) item will limit how much the water can go through the pipe while if "filter" means what substance in the water can go through and which cant such as condiments or minerals contained in water
juz my though