What is the answer to 6x+15=3x+8

Scores on the cognitive scale of the bayley-scales of infant and toddler development range from 1 to 19, with a standard deviation of 3. calculate the margin of error in estimating the true mean cognitive scale score, with 99% confidence, if there are 12 infants and toddlers in a sample.

Which of the following choices gives you a slope of 3?

Which container holds more,a half gallon milk jug or a 2 liter juice bottle