There are 20 people in a room, If they all shake each other's hands once and only once, HOW MANY handshakes are there altogether?

380 Shakes

Step-by-step explanation:

first you need to figure out how many people are shaking the persons hand sou you do 20 x 16 which equals 380

area of part 1:

a1=base*height/2=(8+2)*(8-2-2-1)/2=10*3/2=15 ft^2

area of part 2:

a2=length*width=(8+2)*1=10 ft2

area of part 3:

a3=length*width=8*2=16 ft2

total shaded area : a1+a2+a3=41 ft2

total area of the reactangle : a=16*8=128 ft2

total area of the nonshaded region : 128-41=87 ft2

constants mean the stopped points or the points on a graph that nothing is changing, hope this

step-by-step explanation: