Since each package contains x number of crayons then the total number of crayons would be 7x. Given that the total number of crayons is 42, you'll have the mathematical expression as:
7x = 42
dividing both sides by 7 to get the value of x you'll have
7x/7 = 42/7
x = 6
therefore there are 6 crayons in each pack.