The answer is option three(photo for step by step)
Answer:

Step-by-step explanation:
Let
denotes number of pencils, markers, erasers respectively.
For Andrea:

For Justin:

For Virginia:

On subtracting equations (i) and (ii), we get

Put
in equation (i)

Put
in equation (iii)

Multiply equation (iv) by 5 and equation (v) by 6 and then subtract both the equations.

Put
in equation 

Put
in equation (i)

Answer:
$2x
Step-by-step explanation:
- x × 2 = 2x
I hope this helps!
<u>old:</u> $16
<u>new:</u> $20
<u>percent increase</u>
-> formula: (new-old / old) x 100
(20-16 / 16) x 100
4/16 x 100
0.25 x 100
answer: 25% increase