Answer:

Step-by-step explanation:
Given


Required
Eliminate a
Multiply the first equation by -4

Add to the second equation

Solve brackets

Open bracket


At this point, a has been eliminated;
From the list of given options, the option that answers the question is 
Answer:
Option B.
Step-by-step explanation:
Remember that the profit is defined as the difference between the revenue and the cost.
So, having a profit y = 0 means that the woodworker did not win nor lose anything.
Then the zeros of the function, the values of x such that the graph intersects the x-axis, are the prices such that she does not win nor loss anything.
In the graph we can see that the zeros are at:
x = 15 (the first one)
x = 70 (the second one)
so the zeros are at x = 15 and x = 70, and these are the prices such that the profit is zero, so at these prices she does not make nor lose money.
The correct option is B.
Step-by-step explanation:

Can you help me with my posted questions
When you divide exponents, you have to subtract them. So -4-3= -7 as the exponent
When you have a negative exponent, then you have to flip the fraction (all whole numbers are over 1 so flip the 1 to the top and the 5^7 on the bottom)