<PRE><B>Question 1186206</B>
.
&lt;pre&gt;

Simply, you should add 9 times 4 seats to 50 seats


    the number of seats in 10th row = 50 + 4*9 = 50 + 36 = 86.


The sequence of numbers, presenting seats in each row is

    50. 54, 58, 62, . . . 


each time you add 4 seats to the previous number.


It is so called arithmetic progression.


Its first term is 50.  Its common difference is 4.



The formula for the n-th term is  {{{a[n]}}} = {{{50 +4*(n-1)}}}.



For the 10th term (10th row) you have, according the formula,  {{{a[10]}}} = 50 + 4*(10-1) = 86,

exactly the same number as we obtained above.
&lt;/pre&gt;

Solved and explained.


-----------------


For introductory lessons on arithmetic progressions see 

&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;- &lt;A HREF=http://www.algebra.com/algebra/homework/Sequences-and-series/Arithmetic-progressions.lesson&gt;Arithmetic progressions&lt;/A&gt;

&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;- &lt;A HREF=http://www.algebra.com/algebra/homework/Sequences-and-series/The-proofs-of-the-formulas-for-arithmetic-progressions.lesson&gt;The proofs of the formulas for arithmetic progressions&lt;/A&gt; 

&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;- &lt;A HREF=http://www.algebra.com/algebra/homework/Sequences-and-series/Problems-on-arithmetic-progressions.lesson&gt;Problems on arithmetic progressions&lt;/A&gt;  

&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;- &lt;A HREF=http://www.algebra.com/algebra/homework/Sequences-and-series/Word-problems-on-arithmetic-progressions.lesson&gt;Word problems on arithmetic progressions&lt;/A&gt;

in this site.


Also, &amp;nbsp;you have this free of charge online textbook in ALGEBRA-II in this site

&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;- &lt;A HREF=https://www.algebra.com/algebra/homework/complex/ALGEBRA-II-YOUR-ONLINE-TEXTBOOK.lesson&gt;ALGEBRA-II - YOUR ONLINE TEXTBOOK&lt;/A&gt;.


The referred lessons are the part of this online textbook under the topic &lt;U&gt;&quot;Arithmetic progressions&quot;&lt;/U&gt;.



Save the link to this textbook together with its description


Free of charge online textbook in ALGEBRA-II
https://www.algebra.com/algebra/homework/complex/ALGEBRA-II-YOUR-ONLINE-TEXTBOOK.lesson


into your archive and use when it is needed.



</PRE>