The constant of proportionality should be 45 miles per hour, and the car should travel 135 miles in three hours.
Answer: E: The number of books a person finished reading last month
Step-by-step explanation:
First, a discrete variable is a variable that only can take some given values in a set, the discrete variables are usually not dense, and a continuous variable is a variable that can take any value in a range (where the accepted values are dense).
So, for example, the set of the natural numbers is discrete, and the set of the real numbers can represent a continuous variable.
Here the only option that is really discrete will be the number of books that a person finished reading last month because here only positive whole numbers are accepted (you can not finish a 0.454 of a book)
The other options are continuous because all are classical measures.
For example, the weight of a person can jump between:
75.6kg and 75.7kg.
So you could think that this is discrete because the values between 75.6kg and 75.7g are not shown with our measuring device, but those will be added in the error of the measure because the weights between 75.6kg and 75.7kg are actually possible, so they must be accepted.
Grouping method works best on this one:
<span>ab+a+4+4b=a<span>(b+1)</span>+4<span>(b+1)</span></span>
<span>=<span>(a+4)</span><span>(b+1<span>)
</span></span></span>
<em>A ratio camparing two quantities with different kinds of units is a ratio that tells the rate of change of one variable with a change in other variable.</em>
The correct answer is d.We have the following system of linear equations:
(I)

(II)

Let's use the elimination method, then let's multiply the equation (1)

and subtracting (I) and (II):
(I)

∴

(I)

(II)

____________________
(III)

∴

We can find the value of x by substituting y either in (I) or (II). Thus, from (I):

∴

∴

∴

∴

Let's substitute the values of x and y into (I) and (2)
(I)

(II)

Finally the answer is: