First, you would have to do 11x + 3x Since you're combining like terms.
Now your problem is 14x + 40 = -24
Now you would do 40 - -24 which is now 40+24 and equal to 64.
Now you divide 14 by 64 and you get 4.5
A title could be the effect of the amount/number of days on the amount/number of bacteria. For the 2nd The IV is temperature, the DV is Enzyme Activity and a title could be The effect of Temperature on Enzyme activity.