Can sound waves water waves light waves and sesimic waves carry matter ?

Individuals who live below the poverty line get seriously ill more often than those who do not what could be the hidden variable in this situation?

Air is to be preheated by hot exhaust gases in a cross-flow heat exchanger before it enters the furnace. air enters the heat exchanger at 95 kpa and 20°c at a rate of 0.6 m^3/s. the combustion gases (cp = 1.10 kj/kg°c) enter at 160°c at a rate of 0.95 kg/s and leave at 95°c. determine the rate of heat transfer to the air and its outlet temperature.

What’s #16 asking and how do i solve it?