Agroery store sells a 6-pack of bottled water for $3.79 a 9-pack for $4.50 and a 12-pack for $6.89.which package costs the least per bottle? explain your reasoning.

6 pack for $3.79/// so $0.63 for one bottle
9 pack for $4.50/// so $0.50 for one bottle
12 pack for 6.89 so $0.57 for one bottle

therefore, 9pack for $4.50 is the one that costs least per bottle.

First subtract 10 from both side
y^2+6y-16=0
(y+8)(y-2)=0
-8 and 2