I’m not sure if this is correct but
you have used 3/8 of the plants so you will have 5/8 left to use
Supplementary means it adds up to 180 degrees.
So if one side is 31 degrees, you would need to subtract that from 180 to find the other side.
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180 - 31 = 149
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The other angle would be 149 degrees.
No but , they can be pretty easy sometimes
