The slope is 1, because the slope form is:

Where the m is the slope. Here, m=1.
The vertex is (3,0).
The 3 inside the abs val bar tells you the x value of the vertex is 3. No number outside the abs value bar is a +0 which is the y value of the vertex.
V = (pi)r² h
v = (pi)5² h
v = 25(pi) h
take derivative with respect to h
dv/dh = 25(pi)
(dv/dt)*(dt/dh) = dv/dh
dv/dt is given to be 5 cm³
solved for dv/dh = 25(pi)
5(dt/dh) = 25(pi)
dt/dh = 25(pi)/5
dt/dh = 5(pi)
then the recipricol of dt/dh; we want to find dh/dt = 1/(5(pi))
Increased by 15
past score was x
increased by 15 means he raised to 15+x
it was raised to 83%
therefor
x+15=83
first option is right (and first test was 68%)