The graph shows the relationship between the United States dollar and the euro, the currency of the European Union, in December 2011. Part A: What is the constant of proportionality shown in the graph?

The constant of proportionality is 3/4

Step-by-step explanation:

Here, we want to write the constant of proportionality in the given graph .

To find the constant of proportionality, we need to find the slope of the line.

We can get the slope by using two of the points on the line.

Mathematically, slope of a line m is;

m = (y2-y1)/(x2-x1)

Let (x1,y1) = (120,90) and (x2,y2) = (400,300)

slope will be ( 300-90)/(400-120) = 210/280 = 3/4

Step-by-step explanation:

Answer and step-by-step explanation:

In Adam's expression, d represents the original price of the game.  0.75d represents 75% of the original price; this is the amount of the discount, since everything is 75% off.  Taking the difference of the original price and the discount,

d-0.75d,

gives us the total price of the game.

In Rena's expression, 0.25 represents 25%.  This is because taking 75% off of the price means we still pay 100-75 = 25% of the original price.

Multiplying the original price, d, by the 0.25, gives us 25% of the original price; this is the total price.