#16"oz" = 1"lb"# #2000"lb"=1"t"# (assuming we are using the short ton)
With this, we can multiply #56"oz"# by #1# multiple times, canceling the appropriate units, and obtain
#56color(red)(cancel("oz")) xx (1color(blue)(cancel("lb")))/(16color(red)(cancel("oz"))) xx (1"t")/(2000color(blue)(cancel("lb"))) = 56/(16xx2000)"t" = 7/4000"t"=0.00175"t"#