The answer is C, because 2 shapes can have the same area, but that doesn't necessarily mean they're congruent.
For this case we have the following system of equations:

We solve by the substitution method:
We substitute the first equation in the second equation:

We apply distributive property considering that 

We subtract 69 from both sides of the equation:

We divide by 8 on both sides of the equation:

We look for the value of the variable y:

Thus, the solution of the system is 
Answer:

Answer:
15.6 ft
Step-by-step explanation:
Since the sails are similar then the ratios of corresponding sides are equal.
Comparing the shortest sides, that is
10 : 6 = 5 : 3
let the longest side be x, then using proportion
=
( cross- multiply )
5x = 78 ( divide both sides by 5 )
x = 15.6
The longest side is 15.6 ft
Sure, that's easy! Here's one
5x + 7 = 162
If I wanted to solve this equation, I would break it down. I'd subtract the result (162) by 7
162 - 7 = 155.
From there I just divide that by 5!
155 / 5 = 31
There it is! Ultimate proof that x is in fact 31!
Ms. Alonzo received 400 markers because one tenth of 4000 is 400. Hope this helped!