Eli wants to combine 0.5 gallon of a 10% acid solution with some 35% acid solution to make a 15% acid solution. Which equation can you use to determine how many gallons of the 35% acid solution Eli should add?
a. (0.10)(0.5) + 0.35g = 0.15 (g + 0.5)
b. (0.10)(0.5) + 0.35g = 0.15 (g + 0.5) + 0.15
c. (g + 0.5) + 0.15 = 0.15(g + 0.5)
d. (0.10)(0.5)(0.35g) = 0.15(g + 0.5)

Researchers were interested in whether relaxation training decreases the number of headaches a person experiences. they randomly assigned 20 participants to a control group or a relaxation training group and noted the change in number of headaches each group reported from the week before training to the week after training. which statistical analysis should be performed to answer the researchers' question?