427 x 52 please help and do step by step

The physical fitness of an athlete is often measured by how much oxygen the athlete takes in (which is recorded in milliliters per kilogram, ml/kg). the mean maximum oxygen uptake for elite athletes has been found to be 60 with a standard deviation of 7.2. assume that the distribution is approximately normal.

Two times a number plus three times another number equals 4. three times the first number plus four times the other number is 7. find the numbers

Adam used 1072.4 gallons of water over the course of 7 days. how much water did adam use, on average, each day?