Answer:
18 inches
Explanation:
We are given that Mark wants to hang four rectangular pictures in a row on a wall so that the horizontal space between each picture is always same.
Length of each picture=8 inches
Length of wall=74 inches
Horizontal space before first picture and after the fourth picture=12 inches
We have to find space between pictures.
Let x be the space between pictures



Hence, the distance between pictures=18 inches