Answer:
21 roads
Step-by-step explanation:
If each two cities are connected by a direct road, to find the number of roads we just need to solve a combination of 7 choose 2, that is, we need to find all pairs of two cities among the 7 cities:
Combination of 7 choose 2 = 7! / (5! * 2!) = 7*6/2 = 21
So there is a total of 21 roads on the island.
Answer:
The principal amont was $35,000
Step-by-step explanation:
This is a simple interest problem.
The simple interest formula is given by:

In which E are the earnings, P is the principal(the initial amount of money), I is the interest rate(yearly, as a decimal) and t is the time.
In this problem, we have that:

We want to find P. So





The principal amont was $35,000
Try using PEMDAS,
Parentheses
Exponents
Multiplication
Division
Addition
Subtraction
So just do the problem in that order.
2x-5=11
2x-5+5=11+5
2x=16
x=16/2
x=8
712/8=?
First found out what 71/8 is. 71/8 is 8 and 7/8. This tells that there is 7 left so now you add 7 to two which gives you 72. Then you divide 72/8=9 and combine 8 and 9 which gives you 89. So 712/8=89