The original area of a face would be a^2. Now that you added b to the edge, the new area of each face would be (a+b)^2. To find how much the are increased, subtract a^2 from (a+b)^2.
So the answer is b(2a+b)
The linear function that models the total cost for x deliveries is:

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A linear function has the following format:

In which
- m is the slope, that is, the rate of change.
- b is the y-intercept, that is, the value of y when x = 0.
In this problem:
- Fixed cost of $9 per month,
. - Cost of $2 for each delivery, thus
.
The function for the <u>total cost for x deliveries is:</u>

A similar problem is given at brainly.com/question/16270359
Answer:
£110
Step-by-step explanation:
We know how much time it takes for a boiler and a radiator, and we need to know how much it will cost for 1 boiler and 4 radiators. We have an initial cost of £30, and since hes doing a boiler - which we know takes an hour - we can already add £20 for a start of £50.
Now, there are 4 radiators, that take 45 minutes each. We need to use this equation:

We divide by 60 because there are 60 minutes in an hour, and he charges by hour. So:

Now, to find out how much to charge, we need to figure out how much to add to the £50. Since it's £20 an hour, and it takes 3 hours to do the 4 radiators, we need to multiply:

Now we add our totals for a grand total of...

It would be 7 because -3 times 5