Question 264590
630 miles upstrem = 630/(45-x)
720 miles downstream 720/(45+x)
630/(45-x) = 720/(45+x)
Multiply each side by (45-x)(45+x)
630(45+x) = 720(45-x)
28,350 + 630x = 32,400 - 720x
28,350 + 630x + 720x = 32,400 - 720x + 720x
28,350 + 1350x - 28,350 = 32,400 - 28,350
1350x = 4050
Divide each side by 1350
x = 3
The speed of the currecnt is 3 mph
Check:
630/(45-3) = 720/(45+3)
630/(42) = 720/(48)
15 = 15