Answer:
b=5..............is the answer
Step-by-step explanation:
Let the original speed of the train be x km/h.
Time taken to cover a distance of 360 km = 360/x hours.
New speed of the train = (x+5) km/h.
Time taken to cover a distance of 360 km at new speed = 360/x+5 hours.
Since, the train takes 1 hour less time,
∴360/x - 360/ x+5 = 1
⇒360 (5) = x² + 5x
⇒1800 = x² + 5x
⇒x² + 5x - 1800 = 0
⇒x² + 45x - 40x - 1800 = 0
⇒x (x+45) - 40( x +45) = 0
⇒(x+45) (x-40) = 0
⇒x = (-45), 40
But since speed cannot be in negative.
∴x = 40 km/hr.
Hence, the original speed of the train is 40 km/h.
Answer:
Step-by-step explanation:

Subtract 4 times the first equation from the second:
(-7y +16x -80) -4(-9y +4x -20) = (0) -4(0)
29y = 0 . . . . . simplify
y = 0 . . . . . . . .divide by 29
4x -20 = 0 . . . . substitute 0 for y in the first equation
x -5 = 0 . . . . . .divide by 4
x = 5 . . . . . . . . add 5
The solution to this system is (x, y) = (5, 0).
The relationship is proportional because it is in standard form
Answer: 21
Step-by-step explanation: hope this helps :)