The answer is 69.6 degrees because all of the angles of a triangle always add up to 180 degrees so adding 42 and 68.4 gets 110.4, and then subtracting that from 180 gets 69.9.
The ratio cans to price are 12/15.
Cross multiply: 12/15 * 7/x = 84/15x = x = 5.6
the answer should be 13935/100