How many permutations exist of the letters a, b, c, d taken four at a time?
a.24
b. 12
c. 4

A. 24

Step-by-step explanation:

We are asked to find the number of permutations exist of the letters a, b, c, d taken four at a time.

We will use permutation formula to solve our given problem.  

, where,

n = Total number of objects,

r = Number of objects taken at a time.

We can see total number of letters is 4 and number of letters taken at a time is also 4, so substituting these values in permutation formula we will get,

Therefore, 24 permutations exist for our given letters and option A is the correct choices.

$655.61 which is option c

step-by-step explanation:

price of house =   $146,000

initial rate = 3.5%

mortgaged paid in this = 3.5 % of $146,000

                                        =

                                        =$5110

the total years would be = 7

total mortgaged paid = 7 * $5110

                                      =$35770

remaining money = $146000-35770

                                =$110230

new mortgaged payment = 5 % of 110230

                                            =  

                                            =$655.61