Answer:
105 is the least common denominator
Step-by-step explanation:
Since 7, 5 and 3 are all prime.
LCM would be 7×3×5 = 105
(3x+1) = 64
3x = 63
3x/3 = 63/3
x = 21
Answer:
The rate of the current is 2 miles per hour.
Step-by-step explanation:
Let us assume that the rate of the river is v miles per hour.
The speed of the boat is 12 miles per hour.
Let us assume also that the boat can go 21 miles in t hours in the downstream and 15 miles upstream at the same time i.e. t hours.
So, from the condition given we can write that
......... (1), and
......... (2)
Now, adding those two equations we get
⇒
hours
Now, from equation (1), we get,
⇒ v = 2 miles per hour
Therefore, the rate of the current is 2 miles per hour. (Answer)