Expand the expression 3(7 + x)

How to write 3 tenths and 5 tenths as a decimal

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.

Simplify the expression below -3(10x+4y)+6(6x-2y)