STU + STR = 180
8x + STR = 180 [ STU = 8x ]
STR = 180 - 8x
STR = SRT [ RS ≈ ST ]
Now, In ΔSRT,
we have, RST = 7x - 54, STR = SRT = 180-8x
Their sum is 180, as it constitutes a triangle.
7x-54 + 2(180-8x) = 180
7x - 54 + 360 - 16x = 180
306 - 9x = 180
9x = 306 - 180
9x = 306 - 180
x = 126/9
x = 14
So, option A is your answer.
Hope this helps!
Perimeter is all sides added<span />
Answer:
12
Step-by-step explanation:
The formula of a slope:

We have m = -2 and the points (0, d) and (-8, 9). Substitute:

1) we calculte the driver´s unit rate of speed.
s=speed
d=distance
t=time.
s=d/t
45 miles------------------3/4 hour
x----------------------------- 1 hour
x=(45 miles * 1 hour) / (3/4 hour)=60 miles.
speed or rate=60 miles / 1 hour.
2)we calculate the distance traveled at 1.25 hour.
distance=rate * time
distance=(60 miles /1 hour) * 1.25 hour=75 miles.
Answer: the driver would´t go late, because, the distance is 65 miles, and he can travel 75 miles if he drive with that speed .