Economic models
a. are useful because they do not omit any real-world details.
b. are usually composed of diagrams and equations.
c. are usually plastic representations of the economy.
d. are not useful because they omit many real-world details.

B.are usually composed of diagrams and equations

There are three key entities in thefederal reserve system: the  board  of governors, the  federal reserve banks(reserve banks), and the  federal  open market committee (fomc). while the  federal reserve  has frequent communication with executive branch and congressional officials, its decisions are made independently.

$527.7.if the following was the question  $527.7 is the answer.students who are trying to raise funds have an agreement with a local pizza chain. the chain has agreed to sell them pizzas at a discount, which the students can then resell to families in the local community for a profit. it is expected that of the 500 families in the community, at most 70% will buy pizza. based on a survey of their personal preferences, the students believe that they should order no more than 120 cheese pizzas, no more than 150 pepperoni pizzas, and no more than 100 vegetarian pizzas. they also want to make sure that at least 20% of the total pizzas are cheese and at least 50% of the pizzas are pepperoni. they make a profit of $1.45, $1.75, and $1.98, respectively, for each cheese, pepperoni, and vegetarian pizza they resell. how many pizzas of each type should they buy?