The slope of the function is 2!
2x + 9 = 43 This is the equation.
2x = 34 Subtract 9 from both sides.
x = 17 Divide both sides by 2.
The watch costed $400 before the discount.
76 * 100 = 7,600
7,600 / 19 = 400
Obtuse angles are over 90 degrees but less than 180 degrees. So minimum y can be is 10: (5 x 10) + 45 = 95 degrees (which is more than 90). Maximum for y is 26: (5 x 26) + 45 = 175 (which is less than 180 degrees)