400-(18+705:x)•4=28•5

To solve the equation \( 400 - (18 + \frac{705}{x}) \cdot 4 = 28 \cdot 5 \), we can follow these steps:

1. First, calculate \( 28 \cdot 5 \): \[ 28 \cdot 5 = 140 \]

2. Substitute this back into the equation: \[ 400 - (18 + \frac{705}{x}) \cdot 4 = 140 \]

3. Rearranging the equation gives: \[ (18 + \frac{705}{x}) \cdot 4 = 400 - 140 \] \[ (18 + \frac{705}{x}) \cdot 4 = 260 \]

4. Now, divide both sides by 4: \[ 18 + \frac{705}{x} = \frac{260}{4} \] \[ 18 + \frac{705}{x} = 65 \]

5. Subtract 18 from both sides: \[ \frac{705}{x} = 65 - 18 \] \[ \frac{705}{x} = 47 \]

6. Now, multiply both sides by \( x \): \[ 705 = 47x \]

7. Finally, divide both sides by 47 to solve for \( x \): \[ x = \frac{705}{47} \]

Now, let's calculate \( \frac{705}{47} \): \[ x = 15 \]

Thus, the solution to the equation is: \[ \boxed{15} \]