Answer:
Lixin obtains 15 marks
Step-by-step explanation:
Lets write two equations based on the question where: <u>D= Devi and L=Lixin</u>
D=L+15 <em>- "devi scores 15 marks more than lixin"</em>
D=2L <em>- "devi obtains twice as many marks as lexin"</em>
Now, substitute 2L as D in the first equation we wrote: (D=L+15)
2L=L+15
Next, subtract L from both sides:
<u>L=15</u>
F(x) is a quadratic equation with the x-side squared and a is positive which means that the graph of the function is a parabola facing up. The range of f(x) is given by {y|y ≥ k}, where k is the y-coordinate of the vertex.

, written in vertex form is

, where (h, k) = (-1, -11)
Therefore, range ={y|y ≥ -11}
(10 2/3)/(11/20)
(32/3)/(11/20)
(32/3)*(20/11)
640/33
19 13/33 since DVDs are integer units Mr. Washington can only have 19 DVD's side-by-side.
Answer:
If she walks 5 blocks and it takes 10 minutes each block takes 2 minutes to walk.
10
— = 2 So 2 minutes per block
5