#### Answer

{20}

#### Work Step by Step

$\frac{x}{4}$ - $\frac{x}{5}$ =1
Step 1 : Multiply both the sides by 20
($\frac{x}{4}$ - $\frac{x}{5}$)* 20 =1*20
Solve
$\frac{x}{4}$*20 - $\frac{x}{5}$ * 20=1*20
5x - 4x = 20
Step 2 : Subtract 5x -4x = x
x = 20
Now we check the proposed solution, 20 , by replacing x with 20 in the original equation.
Step 1: the original equation $\frac{x}{4}$ - $\frac{x}{5}$ =1
Step2: Substitute 20 for x
$\frac{20}{4}$ - $\frac{20}{5}$ =1
Step 3: Divide $\frac{20}{4}$ = 5, $\frac{20}{5}$ = 4
5 -4 =1
Step 4 : Subtract 5 - 4 =1
1= 1
Since the check results in true statement, we conclude that the solution set of the given equation is {20}.