Answer:

Step-by-step explanation:
Let's call the numbers "<em>tu</em>", where<em> t</em> is the tens digit and <em>u</em> is the units digit.
We can solve this by the "brute force" method — examining each number to see if it satisfies the conditions.


The question is an illustration of arithmetic sequence.
<em>The number of conversation for 19 people is 171</em>
<u />
<u>(a) 9 people</u>

9 represents the number of people
8 represents the number of conversation each person had
2 represents the number of people having a conversation at once (i.e 2 people at once)
<u>(b) 19 people</u>
We have:

The number of conversation is:

So, we have:




Hence, the number of conversation for 19 people is 171
Read more about arithmetic sequence at:
brainly.com/question/18109692
Answer:it has four side
Step-by-step explanation:
idito
3x = B
(x + 80 = 1/2B) * -3
-3x-240 = -3/2B
-240 = -1/2B
B=480 pennies