If you had 16 tiles and each tile cost 80 cents how much change would you dmget back if you paid with 2 100 bills

16 tiles x 0.80 = $12.80

If you have two 100 dollar bills, you have 200 dollars.

$200 - $12.80 = $187.20

  the   balanced   equation   for   reaction of   ca metal   with   o2 to   produce   cao   is as below

2 ca+ o2→ 2 cao2

  explanation

the reaction is   balanced     since the   number of atoms   in reactant side is   equal to   number of atoms   in   product side.   for   example   they   are 2   atom of   ca in   reactant   side   and   2   atoms of ca   in   the product side.

  the   process   is a   meet the   requirement   of   redox   reaction because :     calcium   is   oxidized   from   oxidation state 0   to 2+   while   oxygen   is reduced from   oxidation   state   0   to 2-