Answer:
$390+0.07s=$544+0.05s Subtract $390 from each side.
0.07s=$154+0.05s Subtract 0.05s from each side.
0.02s=$154 Divide each side by 0.02.
s=$7700 Both plans pay the same when sales=$7700
ANSWER With sales greater than $7700, Chris is better off with Plan A.
Answer:

Step-by-step explanation:
see the attached figure to better understand the problem
step 1
In the right triangle ABC find the length side BC
we know that


step 2
In the right triangle ABD find the length side BD
we know that


step 3
we know that
The distance between the two boats is the length side CD

substitute the values

Just combine like terms: all of the x^2 together, all of the x's together and all of the numbers:
3x2+5x2+5x-2-1
8x2+5x-3 simplified, so letter A
The answer is 10, so it would be C