What will come in the place of question mark (?) in the following questions?

$?+25\times 40=600+35\%\text{of }800$

To find the value that comes in place of the question mark (?), we can set up the given mathematical expression as an equation and solve it step-by-step.

Let the question mark (?) be represented by the variable $x$. The given equation is:

$x+25\times 40=600+35\%\text{ of }800$

First, let's simplify the multiplication on the left-hand side of the equation:

$25\times 40=1000$

Substitute this back into the equation:

$x+1000=600+35\%\text{ of }800$

Next, let's calculate the percentage value on the right-hand side. By definition, "35% of 800" can be written as:

$\frac{35}{100}\times 800=35\times 8$

Calculating the multiplication:

$35\times 8=280$

Now, substitute this value back into our equation:

$x+1000=600+280$

Simplify the right-hand side by adding the numbers:

$600+280=880$

This gives us the simplified equation:

$x+1000=880$

To solve for $x$, subtract 1000 from both sides of the equation:

$x=880-1000$

$x=-120$

Therefore, the value that should replace the question mark is -120.

The correct option is -120.