Question 1184224
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            A quick solution is as follows.



<pre>
Look at the Pascal's triangle in this Wikipedia article

https://en.wikipedia.org/wiki/Pascal%27s_triangle



You will see momentarily that the sought line is the  8th  line for    {{{(1+x)^7}}}.


Those coefficients are  7, 21, 35.


The sum of coefficients at odd degrees is HALF of the total sum, which is  {{{2^7}}} = 128.


THEREFORE, the answer to the problem's question is  128/2 = 64.
</pre>

Solved.