Answer:
x= 3
Explanation:
∠RTS +∠RST= ∠QRT (ext. ∠ of △RST)
(25x)° +(57 +x)°= (45x)°
25x° +x° +57°= 45x°
26x° +57°= 45x°
45x° -26x°= 57°
19x°= 57°
x°= 57° ÷19
x°= 3°
∴ x= 3
Alternatively, find the measure of the angle RST using ∠ sum of triangle then find ∠QRT using adjacent angles on a straight line. Equate this value to 45x and solve for x.