I bottle:
250 * 150mg =Â 37500mg
If 37500mg ------- cost -------Â Â $2.95
so 1mg    ------- cost ------- x
x = 1mg* $2.95 / 37500mg =  $7,87*10â»â”Â
II bottle
125 * 200mg =Â 25000mg
If 25000mg ---------- cost ---------- $3.50
so 1mg    ---------- cost ---------- x
x = 1mg* $3.50 / 25000mg = $0,00014=$1,4*10â»âŽ
$7,87*10â»â” < $1,4*10â»âŽ
1st bottle is better bargain cause 1mg of aspirin its cheaper than in 2nd.