Answer:
15. 9 and 54; 16. 14 and 50; 17. 7 and 62;18. 3 and 50
Step-by-step explanation:
If QR bisects ∠PQS, ∠PQR = ∠RQS
15.
∠PQR = ∠RQS
[tex]\begin{array}{rcl}3x & = & 4x - 9\\0 & = & x - 9\\x & = & \mathbf{9}\\\end{array}[/tex]
∠PQS = 2∠PQR = 2 × 27 = 54
16.
∠PQS = 2∠PQR
[tex]\begin{array}{rcl}4x - 6 & = & 2(x + 11)\\4x - 6 & = & 2x + 22\\4x & = & 2x + 28\\2x & = & 28\\x & = & \mathbf{14}\\\end{array}[/tex]
∠PQS = 4×14 - 6 = 56 - 6 = 50
17
.
∠PQR = ∠SQR
[tex]\begin{array}{rcl}5x - 4 & = & 3x + 10\\5x & = & 3x + 14\\2x & = & 14\\x& = & \mathbf{7}\end{array}[/tex]
∠PQR = 5×7 - 4 = 35 - 4 = 31
∠PQS = 2∠PQR = 2 × 31 = 62
18.
∠PQR = ∠SQR
[tex]\begin{array}{rcl}8x +1 & = & 6x + 7\\8x & = & 6x + 6\\2x & = & 6\\x &= & \mathbf{3}\\\end{array}[/tex]
∠PQR = 8×3 + 1 = 24 + 1 = 25
∠PQS = 2∠PQR = 2 × 25 = 50