Step-by-step explanation:
We can start by writing an equation to describe the data set. For 2D data, one equation form we can use is y=m*x + b, where x is the input and y is the output. Since yuan are put in and dollars are put out, x represents yuan and y represents dollars in this instance.
To find the equation, we can start by plugging in two points, such as (50, 1.25) and (100, 7.5). The slope, or m, is equal to the change in y/change in x, or
(7.5-1.25)/(100-50) = 6.25/50
= 0.125. This means that for each yuan put in, 0.125 dollars come out, according to the formula.
Next, we must find b. Plugging 0.125 in for m and taking a set of points, such as (50, 1.25), we get
1.25 = 50(0.125) + b
1.25 = 6.25 + b
subtract both sides by 6.25 to isolate the b
-5 = b
Therefore, we can write our equation as
y = 0.125 * x - 5
In this equation, there is an exchange rate of 0.125, meaning that for each yuan put in, 0.125 dollars are coming out. The -5 symbolizes that for each transaction, 5 yuan are being lost, which is the fee for exchanging money.
To check if the equation works, we can try it for options such as (200, 20) and (250, 26.25). This does work, so we can move forward with our equation.
For (c), our equation is y = 0.125 * x - 5, with the y representing dollars, x representing yuan, 0.125 representing the exchange rate, and -5 representing the fee for exchaning mone
For (b), because 5 yuan are subtracted from the exchange rate for each transaction, it is fair to assume that there is a fee for exchanging money. There is a fee of 5 yuan per transaction. In dollars, using the exchange rate of 0.125 dollars per yuan, this is equal to 0.625 dollars
For (a), the exchange rate is 0.125 dollars per yuan. We know this because for each yuan put in, 0.125 dollars are coming out after taking into account the fee
. 
. So the sum is 
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