h=20w
in one week hector works 20 hours
in two hector works 40 etc
h = hours and w = weeks. the money is just extra information.
h=20w works because if it has been two weeks we substitute the w with the number 2 and can solve
h=20(2)
h=20x2
h=40
This proves that the equation is true
I bet you're doing the Law of Sines right now. If you use the law of sines you find out that angle A is a 90 degree angle. There is only one triangle you can make with these measurements because if you have one angle of 30 and another of 90, the 3rd angle has to be a 60 degree angle. So it is a special right triangle, 30-60-90