<span>from the whole price,
15% of this price is equal to $18.00.
therefore if 15 % equals $18.00
then 100% is the original price therefore 100 % = 18.00 / 15 % x 100% = $120 therefore original price = $120</span>
X = small van capacity, y = larger van capacity
y = x + 6
2x + y = 57
now we sub in x + 6 for y
2x + x + 6 = 57
3x + 6 = 57
3x = 57 - 6
3x = 51
x = 51/3
x = 17
y = x + 6
y = 17 + 6
y = 23
small van (x) has 17 seats and large van (y) has 23 seats
All we need is to put this form in the vertex form f(x) = (ax+b)^2 + c
So we have <span>f (x)= 3x^2+12x+11 ....
Let's complete the square (if you aware of it)
</span><span>
f(x)= 3x^2+12x+11 = 3(x^2+4x)+11 = 3(x^2+4x+4-4)+11
=</span><span> 3([x^2+4x+4]-4)+11 = 3[(x+2)^2-4]+11 =3</span><span>(x+2)^2 - 12 +11 = 3</span><span><span>(x+2)^2 -1
so our form would be:

Here is a parabola with vertex of (-2,-1) and with positive </span> slope (concave up)
</span>
I hope that
helps!