A car travels for 6 hours at different speeds. For the first two hours at 60 m/s, for the next 2 hours at 50 m/s and for the remaining time at x m/s. If the average speed for the entire journey is 52 m/s, what is the value of x?

1 hour = 3600 seconds

2 hour = 7200 seconds

Here the total distance will be calculated by the sum of the product of the different speed with their time intervals respectively. 

Average speed = $$\frac{total\ dis\tan ce}{total\ time}$$

$$52=\frac{60\times\ 7200+50\times\ 7200+x\times\ 7200}{7200+7200+7200}$$

$$52=\frac{7200\left(60+50+x\right)}{21600}$$

$$52=\frac{\left(110+x\right)}{3}$$

$$52\times3=110+x$$

110+x = 156

x = 156-110

x = 46