[probability] there are four people in a room that haven't met before. they are told to shake hands, exactly once, of every other person in the room so that they all meet each other. if each of these people shake their hands with every other person exactly once then how many handshakes are going to occur?

6

Step-by-step explanation:

Let the 4 people be A, B, C and D. If each of them shakes hands with another person exactly one time then that means

A shakes with B, C and D. So 3 handshakes

B already shakes with A. So B shakes with C and D. 2 handshakes

C already shakes with A and B. So C shakes with D only. 1 handshake.

D already shake hand with all above.

Total handshakes: 3 + 2 + 1 = 6

answer:   expression= p+p*d%

price reduction + sale price = $625

sale price: $p+$p*d%

where d% is the percentage of discount

step-by-step explanation:

original price = p

price went down by $150 price reduction $p*d%

sale price= $ 475

therefore the price before sale is: $625

and the expression that shows the price before sale is: p+p*d%