We will have that we will need the following number of boards:
We can see that each board can be used to obtain 6 two-foot braces.
So, we will need:
[tex]x=\frac{1\cdot20}{6}\Rightarrow x=\frac{10}{3}\Rightarrow x\approx3.33[/tex]So, we will need 4 boards.
