Question 1139329
Think about the data given.  Quadratic model with vertex (6, 19) and two points being  (0, 10)  and (12, 10).


{{{y=a(x-6)^2+19}}}

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{{{a(x-6)^2=y-19}}}

{{{a=(y-19)/(x-6)^2}}}
from here, any non-vertex point can be used for evaluating "a".
Trying  (0,10):


{{{a=(10-19)/(0-6)^2=-9/36=-1/4}}}


{{{highlight_green(y=-(1/4)(x-6)^2+19)}}}
Do the necessary multiplication in order to find b.
Already seen are {{{a=-1/4}}}, and {{{c=19}}}.