The area of the shape is 230 cm.
Let p be the prize of a pen and m the prize of a mechanical pencils. If you buy six pens and one mechanical pencil, you spend 6p+m. We know that this equals 9, because you get 1$ change from a 10$ bill.
Similarly, if you buy four pens and two mechanical pencils, you spend 4p+2m, which is 8$, because now you get a $2 change. Put these equation together in a system:

Now, if you multiply the first equation by 2, the system becomes

Subtract the second equation from the first:

Plug this value into the first equation to get

Answer:
In 6 months (at the fifth month they are equal in price)
Step-by-step explanation:
Set the month as x.
Plan A's equation: 8x + 25
Plan B's equation: 12x + 5
8x + 25 < 12x + 5
Solve.
-4x < -20
x > 5
In 6 months (at the fifth month they are equal in price)
choices? i cant tell without choices