To decrease this amount by 15% we must first find out what is 15% percent.
We can do that by multiplying the decimal of 15% by 120
15% = 0.15
0.15 x 120 = 18
So 18 is 15% of 120.
Wait! that's not the answer. We are asked to decrease by 15%
So 120 - 18 = 102
Your answer is £102
1) This is a combination, so use ⁴⁰C₂.
⁴⁰C₂ = 780
There are 780 handshakes in total.
2) I got my solution by using the combinations formula. Or another way you could do this is to add up... 39 + 38 + 37 + 36 + 35 + 34 + 33 + 32 + 31... +1. You will end up with 780 (I did this to double check my work).
3) The quickest way to figure this out if Drake invited 1,000 people is to use the natural numbers formula = n(n+ 1)/2.
Plug the numbers in: 999(1000)/2 = 499,500
If Drake invited 1,000 people, there would be 499,500 handshakes.
Answer: A and B
Explanation: If you draw the graph out it crosses the points (1,2) and (-1,-2) and those are points A and B
