Answer:
The greates amount she could buy is 4
The graph will cross at the coordinates (-2, 9)
<h3>How to solve equations?</h3>
y = 3x + 15
y = 3 - 3x
y = 3x + 15
Hence,
when x = 2
y = 3(2) + 15 = 21
when x = 0
y = 3(0) + 15 = 15
y = 3 - 3x
when x = 2
y = 3 - 3(2)
y = 3 - 6
y = -3
when x = 0
y = 3 - 3(0)
y = 3
Therefore, let's check if the equation will cross.
y = 3x + 15
y = 3 - 3x
using substitution,
3 - 3x = 3x + 15
3 - 15 = 3x + 3x
- 12 = 6x
x = -12 / 6
x = -2
y = 3 - 3(-2)
y = 3 + 6
y = 9
Therefore, the graph will cross at the coordinates (-2, 9)
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no it is not simplified because there are two y values
Answer:

Step-by-step explanation:
Probability refers to chance of happening of some event.
Conditional probability is the probability of an event A, given that another event B has already occurred.
denote the two boxes.
In box
:
No. of black balls = 1
No. of white balls = 1
In box
:
No. of black balls = 2
No. of white balls = 1
Let B, W denote black and white marble.
So, probability that either of the boxes
is chosen is 
Probability that a black ball is chosen from box
= 
Probability that a black ball is chosen from box 
To find:probability that the marble is black
Solution:
Probability that the marble is black = 