Answer:
I think its the first one but I dont remember
<h2>The answer is A) 4.</h2><h2>step by step explanations is in the picture.</h2>
Answer:

Step-by-step explanation:
Given


Required
Determine 
In functions;

So, we have:


Substitute values for R(x) and C(x)

Open bracket

Collect Like Terms


Let, the speed of boat = x
Speed of current = y
So, x + y = 280/7
x + y = 40 ---- first equation
x - y = 280/14
x - y = 20
x = 20 + y
Substitute this value of x in first equation,
20 + y + y = 40
2y = 40 - 20
y = 20/2
y = 10
Substitute this in first equation,
x + 10 = 40
x = 30
In short, Speed of Boat = 30 mph, & speed of current = 10 mph
Hope this helps!
Answer:
what are the opitions
Step-by-step explanation: