Every person at a party of twenty eight people said hello to each of the other people at the party once. How many "hellos" were said at the party?

756 hellos

Step-by-step explanation:

Each 28 persons say hello once to every 27 persons

So, 28 × 27= 756

step-by-step explanation:

given perimeter: 28cm

length: 9cm

atp,

2(l+w)=p of the reactangle

2(9+x)=28

18+2x=28

2x=28-18

x=10/2

x=5

therefore width is 5 cm

y < -3

step-by-step explanation:

-3y - 2 > 7

-3y -2 + 2 > 7+2

-3y > 9

-3y/-3 < 9/-3   (change the inequality sign when multiplying or dividing by a negative number)

y < -3