The answer should be b according to me
I think you mean

basically that measn yo divide that term by the previous term
ok
a3=a1/a2=1/2
a4=a3/a2=(1/2)/2=1/4
a5=a4/a3=(1/4)/(1/2)=1/2
a6=a5/a4=(1/2)/(1/4)=2
a7=a6/a5=2/(1/2)=4
a8=a7/a6=4/2=2
a9=a8/a7=2/4=1/2
a10=a9/a8=(1/2)/2=1/4
ok, so notice a pattern
a3=a9
a4=a10
I therefor conclude that

where w is a whole number
and n>2ok, so
241=6*39+7
so therefor

therefor the 241th term is same as a7 or 4
I say a241 is 4
Answer: After 5 hours, Mary will be at the break even point.
To answer this question, we need to find the time when the cost equals the revenue.
Therefore, set our equations equal to each other and solve.
20 + 30h = 10h^2 - 80
0 = 10h^2 - 30h - 100
0 = h^2 - 3h - 10
0 = (h - 5)(h + 2)
Our solutions are h = 5 or h = -2. Only 5 hours makes sense in the context of this problem.
Answer:
Elimination isn't exactly the easiest for this situation. But since the equations are in the same form and not solved for the same variable, I would go with elimination. (If they were solved for the same variable, I would go with substitution.) It would require me to make a manipulation on both equations.
I would multiply first equation by 5 and second equation by -2. The reason I would do this is because the y's would have opposite coefficients and when you add opposites you get 0.
The new set of equations would look like this:
20x+10y=45
-14x-10y=2
But I will slope here since we aren't asked to solve it.
Some texts use the term linear combination instead of elimination. They are the same.