So 4 hours for 40 dresses.
1 hour would be 40/4=10 dresses
50 dress = 1hr x 5 = 5 hrs#
To solve for the value of x, you can simply add all of the values and expressions together and make it equal to 180 degrees, since the sum of all angles in a triangle add up to this amount.
Then we can solve for X, by algebra.
It is 766666666666666666666666666