Answer:
∠ QRS = 43°
Step-by-step explanation:
The sum of the 3 angles in a triangle = 180°
Sum the 3 angles and equate to 180
4n - 9 + 5n - 18 + 90 = 180, that is
9n + 63 = 180 ( subtract 63 from both sides )
9n = 117 ( divide both sides by 9 )
n = 13
Thus
∠ QRS = 4n - 9 = 4(13) - 9 = 52 - 9 = 43°
∠ RSQ = 4n - 18 = 4(13) - 18 = 65 - 18 = 47°
