178.50 = 11.90y + 10.50x ⇒ equation in standard form.
A quadratic equation has either two different real roots, one real root, or two conjugate complex roots (this is the case when the discriminant is negative, i.e. when you have no real roots).
Two conjugate complex roots have the same real part and opposite imaginary parts. So, the solutions to Amina's equation will be in this form:
For some 
12 problems = 30 minutes
24 problems = 60 minutes
36 problems= 90 minutes
48 problems = 120 minutes
60 problems = 150 minutes
Mary can respond 60 problems in 2 hours and 30 minutes/ 2 hours and half/ 150 minutes.
Hope this helps xx
The vertex form of the function gives the vertex as (-6,48). The vertex of f(x)=x^2 is (0,0) so from this information, the vertex is moved LEFT 6 and UP 48. This cancels out two options. The coefficient -3 tells us that the graph is flipped or reflected over the x-axis (negative sign flips graph) and that all y-values will be 3 times as large. Larger y-values for the same x inputs makes the graph narrower.
