Answer:
B. m∠RTS = 78°
Explanation:
The sides GH and GI of ΔGHI have the same length, so their opposite angles, ∠I and ∠H will have the same measures. Call that measure "x".
The sum of angles in a triangle is 180°, so we have ...
24° +x +x = 180°
2x = 156° . . . . subtract 24°
x = 78° . . . . . . divide by 2
The triangle similarity statement tells you that ∠T will have the same measure as ∠I, which is x, or 78°.
m∠RTS = 78°