Find the missing side length

Which of the following points is collinear with (-2,1) and (0,3)

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.

Solve the following pair of equations for x and y: ax/b_ by /a= a +b; ax - by = 2ab