I will do a and b and you do the rest.
For (a), the equation is x + y = 154.
For (b), the equation is 320x + 85y = 14,970.
We have two equations in two unknowns.
Use the substitute method to find x and y (the given c). Once you have x and y, use that to find d.
Take it from here.
If we randomly pick two persons from the population, each one will have a probability of 1-1/28=27/28 of being a non-carrier.
Thus for neither to be non-carrier, the probability is the product of the individual probabilities since the picks are assumed independent (with a large enough population).
Probability = (27/28)*(27/28) = 729/784
or approximately 0.930
C because x represent the cost of books while 2 can be an additional price for the pens
