There are two rows and five couples. Number of ways in which we can arrange all husbands and wives so that no husband comes in back and front of his wife?

here A is the first row and B be the second row

since the no of couples are five

first row can take any one male from the couple so the no of ways one husband can be placed in row A = 5

since one among all the 5 females is the persons wife therefore only fur persons can stand in second rows

now the toal no of pairs is as for one man there are 4 women therefore for toal of 5 men there are 5*4=20combinatios are possible

yo man all d best