So, h(t) is how far is Daniel's head from the surface of the water, namely the surface itself is when the height is nill, so his head is at the surface and the height of it is just 0, thus h(t) = 0. Namely, what is "t" when h(t) is 0?

clearly the seconds cannot be a negative unit, so is not -3/2.
Slope: 1/40
tell me if i’m right
You have 2 equations that are both equal to y. If they are both equal to y, then by the transitive property of equality, they are equal to each other (if a = b, and b = c, then a = c).
5x - 17 = x + 3 and
4x = 20 and x = 5. Now sub in that x value of 5 to solve for y:
y = 5 + 3 and y = 8. So the ordered pair is (5, 8)
The table tells us that the x coordinate. It also tells us that y is always x + 1.
For #1 you plot the coordinate (0, 1).
0 (the x coordinate) is given to us already.
1 (the y coordinate) is needed to be found by the equation.
You would then need to fill in the equation given with the x coorident.
y = 0 + 1
Then, solve for y.
0 + 1 = 1
The y coordinate is 1
Go to the horizontal line (x) and find 0.
Then go to the veridical line (y) and find 1.
Then match up the the x and y to plot the coordinate.
You would continue with this equation with the rest of the xs.
This is a hard concept to explain in just words, so feel free to comment with any more questions. :D
Answer:
t represents the time in minutes since the balloon started descending.
a(t) represents the altitude of the balloon at t minutes.
a(5.5) gives the altitude at 5.5 minutes.