What is 2.2r+7=18+7.7r

Can someone me with these two circle theorem questions asap?

52 cm radius = diameter = area = circumference = circumfer

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.