The answer is 2 hours and 15 minutes
X=-b/2a is the formula for finding the axis of symmetry
So x= -30/2(5)
X=-30/10
X=-3
Because the axis of symmetry is -3, we know where to place our line, and we also know that the parabola is open downwards, which means that the vertex will be maximum. To find the vertex, plug in your values with the axis of symmetry as a midway point. Plug that in for x and so you should have the following:
F(x)
Y(f(x) and y variables are interchangeable) =5(-3)^2-30(-3)+49
Solve for y(f(x))
5(-3)^2-30(-3)+49
(-3)^2=3^2
3^2*5+30*3+49
Multiply
3^2*5+90+49
Add numbers
3^2*5+139
9*5=45
45+139=184
Y=184
So, your vertex would be
(-3,184) and it would be maximum. From there you can plug in the rest of your table of values.
I believe it is A and Yes
The bigger the price is on an item, the more tax you would have to pay, so both numbers increase. As for whether or not there is a line through the dots, you use a line when you could go inbetween the points. For example, with this question you can have 0.24, 0.86, or any other number as the price and it would make sense. If the question was sales tax on a certain number of shirts, well, you can't buy half a shirt so you don't need anywhere inbetween the dots.
Proportional in these kinds of problems means whether or not the line curves. If it doesn't and is a straight line, then it is proportional.
Ok, so we know that RST is equal to 6x+12
And RST is also equal to 78 + 3x-12
so we set them equal to each other
6x + 12 = 3x - 12 + 78
And simplify
3x = 54
x = 18
Finally, we solve for the angle with 18 for x
6(18) + 12
108 + 12
120
Hope this helps
