240 stokes
Step-by-step explanation
Step 1
find the area of the wall
remember the area of a rectangle is given by:

then
let.

to operate , we need to have the same unit of measure, so we need to convert ft(') into inch(')
remember that
12 inches = 1 ft
hence

now, replace in the formula to find teh area of the wall

Area of the wall = 24180 squared inches
Step 2
now, we to find the area of each stoke ( also a rectangle)
then
Let

to operate we need to convert the mixed numbers into improper fractions,
remember how to do that

therefore,

so

now, let's replace in the formula to find the area of each stoke

Area of echa stoke: 100.75 squared inches
Step 3
Finally, to get the number of stones that will take to build the wall, we need to divide the total area, by the area of one stoke
so

replace

hence
the answer is
240 stokes
I hope this helps you