Lunch costs 15.41 and you need to add a twenty percent tip. There are two ways to do this:
Way 1:
Twenty percent in a decimal is 0.2, so multiply 15.41 by 0.2. After multiplying 15.41 by 0.2 you receive 3.08. 3.08 is the tip, so add the tip to the total meal to receive 18.49.
Way 2:
Twenty percent in a decimal is 0.2 but to add in the cost of lunch multiply 15.41 by 1.2. Why because you add the percent of lunch and tip to a total of 120 percent for the cost of lunch is the total, 100 percent.
Since it forms a "right triangle" we can apply trigonometry. sin x = oppo/hyp sin x = 13/20 x = sin^-1(13/20) x = sin^-1(0.65) x = 40.5 rounded to nearest degree x = 41 degrees
