Barry's deck of cards contains 40 blue cards and 70 red cards max's deck of cards contains the same number of blue cards but the ratio blue cards to red cards 8: 9 how many total cards do s max's deck of cards contain

How do you solve a question like this?

The birth weights of newborn babies in the unites states follow in a normal distrubution with a mean of 3.4 kg and standard deviation of 0.6 kg. reaserches interested in studying how. children gain weights decide to take random samples of 100 newborn babies and calculate the sample mean birth weights for each sample

If x varies directly as y, and x = 7.5 when y = 10, find x when y = 4