Let f be the height of the fir trees
Let p be the height of the pine trees
We know from the problem that
f + p = 21 and 4f = 24 + p
rearrange the 2nd equation to get p = 4f - 24 and substitute into the other equation
so...
f + 4f - 24 = 21
5f - 24 = 21
5f = 45
f = 9 - height of the fir tree
substitute back into the 1st equation
9 + p = 21
p = 12 - height of the pine tree
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Explanation:</h2><h2>
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The diagram is missing but I'll assume that the arc BDC is:

And another arc, let's call it FGH. measures:

If those arc are equal, then this equation is true:

Substituting k into the first equation:

<span>400,958,6 Hope this helps!</span>