Answer:
Here, BRX and NJY are two triangles in which,
BR = 30 cm, RX = 40 cm, BX = 60 cm, NJ = 15 cm, JY = 20 cm and NY = 30 cm,
Also, m∠B = m∠N, m∠R = m∠J and m∠X = m∠Y,
By the property of congruence,
,
and 
Thus, By AAA similarity postulate,

Hence, proved.
Answer:
sedan = 26 miles/gallon
truck = 17 miles/gallon
Step-by-step explanation:
try to write the text in mathematical format as a system of equations
t=truck s=sedan

first equation can be written as
t= (181-5s)/3
we can use it in the second equation and rewrite it as
7[(181-5s)/3]+6s = 275
7(181/3 -5/3s) + 6s = 275
1267/3 - 35/3s + 6s = 275
-35/3s + 18/3s = 275-1267/3
-35/3s + 18/3s = 825/3 - 1267/3
-35s + 18s = 825 -1267
-17s = -442 s = 442/17 = 26 sedan has an average of 26 miles/gallon
we use this value of s in the first equation
3t + 5*26=181 3t=181-130 t= 51/3 = 17 truck has an average of 17 miles/gallon
The maximum value is actually the maximum of y
So, you don't need to care about the stuff inside cosine function,
Cosine function is always within the range of [-1,1]
So here, ymax = -1 + 6* 1 = 5
X = 2
4x + 8 = 16
-8 -8
----------------
4x= 8
-- --
4 4
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x=2