The answer is 18 just add them
Recall your d = rt, distance = rate * time.
now, if the boat has a speed of say "b", and the current has a speed of say "c", when the boat is going upstream, is not really going "b" fast, is going " b - c " fast, because the current is eroding speed from it, going upwards.
And when the boat is going downstream, is not going "b" fast either, because the current is now adding to speed to it, so is really going " b + c " fast.
The time it took one way, is the same time it took back, 4 hours each way.
thus

what's the speed of the boat? well, 5 + c = b.
Given:
Circumference of a circle = C
Diameter of a circle = d
To find:
The relationship between the circumference, c, and diameter, d, of any circle.
Solution:
We know that, circumference of a circle is

It can be written as

![[\because d=2r]](https://tex.z-dn.net/?f=%5B%5Cbecause%20d%3D2r%5D)
On dividing both sides by d, we get

Therefore, the correct option is (F).
Is this a year 9 question and if yes I do not have a clue lol
To solve this, you need to isolate/get the variable "u" by itself in the inequality: u = unknown number
2u - 3 < 1 Add 3 on both sides
2u - 3 + 3 < 1 + 3
2u < 4 Divide 2 on both sides to get "u" by itself
u < 2 (u is any number less than 2)
When the inequality sign is >/< (greater than/less than), the dot/endpoint is an open/unfilled circle.
When the inequality sign is ≥/≤ (greater than or equal to/less than or equal to), the dot is a closed/filled circle.
u < 2
Start making a ray by placing an open circle on 2(click on the dot/endpoint to change it to be open if it isn't already), then have the ray point left where the numbers would be decreasing because "u" is any number less than 2. If you can place the end of the ray at the end of the number line.