if we know that circle is 7, subtract that from 27. You now have 20. So take out the circle in the second problem.
<u>Pentagon</u> + Square = 20 .
<u>Pentagon</u> +<u>Pentagon</u> + Sqaure =28. Adding a Pentagon to the third problem makes it go from 20 to 28. Looking at the second problem you know that 8 + Square = 20. Subtract 8 from 20. You now have 12.
Since you know the circle is 7, the square plus the pentagon must be 20. That means the pentagon in the third equation is 8. This means the square is 12.