Answer:
he is using it correctly
Step-by-step explanation:
he is using it correctly because the bottom line of the angle matches with the 0° line on the protractor.
The answer is A, the denominator should be 18.
The equation is y = 20(1.40)^x
where x is the number of days and y is the future amount after x days go by
The 1.40 is from the fact that 1+r = 1+0.40 = 1.40, where r is the decimal form of 40%, so r = 0.40
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Plug in x = 7 to get
y = 20(1.40)^x
y = 20(1.40)^7
y = 210.827008
y = 211
We round to the nearest whole number since it doesn't make much sense to have a fractional portion of an algae. After 7 days, there are about <u>211</u> algae.
When we build integers from natural numbers, we're looking for additive inverse of natural numbers?
What's an additive inverse? Well, for example, the additive inverse of 2 is a numbers
such that

We call this number -2. So, the real meaning behind the negative sign is "if you add me and my positive counterpart, the result is zero".
So, -5 is the additive inverse of 5, -16 is the additive inverse of 16, and so on, because

Note that this is a symmetrical relation: if -5 is the inverse of 5, it is also true that 5 is the inverse of -5.
So, when you write something like

it means that you want to add 5 and the inverse of the inverse of 4. But given what we just said, the inverse of the inverse of a number is the number itself, which is why subtracting a negative number is the same as adding it.