The whiteboards she bought cost $35, and she spent a total of $51.20, subtract to find out the total amount she spent on posters:

So she spent a total of $16.20 on posters, now divide by the amount one poster costs to find out how many posters she bought.

So she bought 3 posters.
Answer:
Need the graph for final answer. Use the values of the graph to substitute into the slope formula and simplify.
Step-by-step explanation:
The average rate of change is the amount over an interval the outputs change in a ratio to the input change. In a linear function, this is constant and called slope. In all other function, it is called the average rate of change because the rate of change varies over the interval. We use the same formula for the average rate of change as we do slope. First we need both the input and output values of the function over the interval.
Slope:
Substitute the values for your function into the slope formula and simplify.
9/15 as a percent is 60%, so D.
4 1/5 as a percent is 420%, so B.
Answer:
12
Step-by-step explanation:
240-60
then devided by
15