7x+3x=280
10x=280
x=28
John 7*28= 196$
Peter 3*28=84$
The question is asking how many combinations of two people can be made from a group of ten people.
Using the formula C(10,2) = 10!/(2! x (10 - 2)! = 10!/(2! x 8!) = 45 handshakes.
A simple way to prove this is each person shakes the hand of 9 other people
10 x 9 = 90 but this counts every handshake from the view of both people involved.
The actual number of handshakes is therefore 90 / 2 = 45
Answer:
A + 8 = c
Or
A = c - 8
Step-by-step explanation:
Given a = b + 12 we can substitute that in for
b = c + 4.
a + 12 = c + 4
This means
A + 8 = c
Or
A = c - 8
:)