Josh is incorrect, he did not examine the expression correctly, therefore his answer was wrong.
Answer:
We can note that this part of the graph is a linear function. This means that is has a general form: y = mx + c where m is the slop and c is the y-intercept (value of y at x=0). For the slope, we will use the points (0,2) and (3,5) to calculate it as follows: m = (y2-y1)/(x2-x1) = (5-2)/(3-0) = 1 For the y-intercept, we can note that at x=0, the value of y is 2. This means that the equation of the first part of the graph is: y = x + 2
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Interest = Pin = principal * interest rate * number of years
Let interest rate be i, then
600*i*2+150*i*4=90
1200i+600i = 90
i=90/(1200+600)=90/1800=1/20=0.05 or 5%
The best way to solve this problem is by plugging in each answer choice for both equations and seeing which one works. You can already see that choice A doesn't work because -1 is not greater than or equal to 4. That means you just need to test choices B and C!
Choice B (4, -2)

2 is not greater than or equal to 6, so choice B doesn't work.
Choice C (4, 2)

Since 6 is equal to 6 and 4 is equal to 4, choice C works!
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Answer: C) (4, 2)