<span>Each team in the softball league plays each of the other teams exactly once. For every game, there is 2 team playing. The order is not important because A vs B is same as B vs A
So you just need to makes a combination of 2 that have a result of 21. If there is t number of teams, the number of matches would be:
tC2 = t!/2!(t-2)! = 21
</span>t! / (t-2)! = 21 *2
(t)(t-1)= 42
t^2 -t -42=0
(t-7)(t+6)
t=7 ; t=-6
Excluding the minus result, you got 7 teams.
Answer:
20.
Step-by-step explanation:
P(5,3) = 5! / 3!
= (5*4*3*2*1) / (3*2*1)
= 20.
Answer: you bought 9 burgers and 16 tacos
Step-by-step explanation:
Let x represent the number of burgers that you bought.
Let y represent the number of tacos that you bought.
You buy a total of 25 burgers and tacos. It means that
x + y = 25
The burgers cost $3.50 each and the tacos cost $2.25 each. The total cost of the burgers and tacos that you bought is $67.50. It means that
3.5x + 2.25y = 67.5- - - - - - - - - - - - 1
Substituting x = 25 - y into 1, it becomes
3.5(25 - y) + 2.25y = 67.5
87.5 - 3.5y + 2.25y = 67.5
- 3.5y + 2.25y = 67.5 - 87.5
- 1.25y = - 20
y = - 20/ - 1.25
y = 16
x = 25 - y = 25 - 16
x = 9
