Mell ordered 3 times as many hamburgers as cheeseburgers, and four more orders of french fries than cheeseburgers. There were a total of 49 items in his order. How many hamburgers did Mell order? Please add an equation at the end, with a variable

Is the square root of 4 plus the square root of 16 rational?

The owner of the plant nursery where you were tells you to fill 350 ml bottles from a 30 l from a fertilizer

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.