The pairs of goldfish Tasha can buy for $20 are 
Step-by-step explanation:
To find the how many type of goldfish that Tasha can buy for $20 is the set of positive ordered pairs.
Let x denote the number of fancy goldfish.
Let y denote the number of common goldfish.
To find how much goldfish can Tasha buy for $20 is to substitute the value for x in the equation 
Now, substituting 
in , we get,
The ordered pair is 
Similarly, substituting 
,
For 
,
For 
,
For 
,
For 
,
For 
,
Thus, the pairs of goldfish Tasha can buy for $20 are
In algebra, it is easy to find the third value when two values are given. Generally, the algebraic expression should be any one of the forms such as addition, subtraction, multiplication and division. To find the value of x, bring the variable to the left side and bring all the remaining values to the right side.
Answer:
a) Minimize 
subject to
b) Attached
c) The optimum value that minimizes cost is x1=28 and x2=8.
Step-by-step explanation:
The objective function is the cost of extraction and needs to be minimized.
The cost of extraction is the sum of the cost of extraction of ore type 1 and the cost of extraction of ore type 2:
Being x1 the tons of ore type 1 extracted and x2 the tons of ore type 2.
The constraints are the amount of minerals that need to be in the final mix
Copper:
Zinc
Magnesium
Of course, x1 and x2 has to be positive numbers.
The feasible region can be seen in the attached graph.
The orange line is the magnesium constraint. The red line is the copper constraint. The green line is the zinc constraint.
The optimal solution is found in one of the intersection points between two constraints that belong to the limits of the feasible region.
In this case, the cost can be calculated for the 3 points that satisfies the conditions.
The optimum value that minimizes cost is x1=28 and x2=8.
