There would be 12 people at the party!
In general, with n+1 people, the number of handshakes is the sum of the first n consecutive numbers: 1+2+3+ ... + n.
Since this sum is n(n+1)/2, we need to solve the equation n(n+1)/2 = 66.
This is the quadratic equation n2+ n -132 = 0. Solving for n, we obtain 11 as the answer and deduce that there were 12 people at the party.
Since 66 is a relatively small number, you can also solve this problem with a hand calculator. Add 1 + 2 = + 3 = +... etc. until the total is 66. The last number that you entered (11) is n.
Hope this helps!
Answer:
c
Step-by-step explanation:
you have a calculator dont you?
Answer:
x = 80
Step-by-step explanation:
Total = 360
90 + 50 + 90 + 50 = 280
360 -280 = 80
The time when the two trains reach each other is 1.25 hours
The trains are 68.75 away from the city when they reach each other.
Answer:
Cost of 500 g of standard pack = € 7.50
Cost of 1 g of standard pack = 7.50/500
Cost of 100 g of standard pack = 7.50/500 ×100
= 7.50/5
= € 1.50
Hope it helps uh dear
