To solve the equation \(\sqrt{c+100} - c + 10 = 0\), we can isolate the square root term and then square both sides to eliminate the square root. This will result in a quadratic equation in terms of \(c\), which we can solve using the quadratic formula or by factoring.
Step 1: Isolate the Square Root
Starting with the equation:
\[
\sqrt{c + 100} - c + 10 = 0
\]
we can isolate the square root:
\[
\sqrt{c + 100} = c - 10
\]
Step 2: Square Both Sides
Next, we square both sides to eliminate the square root:
\[
c + 100 = (c - 10)^2
\]
Expanding the right side gives:
\[
c + 100 = c^2 - 20c + 100
\]
Step 3: Rearrange to Form a Quadratic Equation
Rearranging the equation leads to:
\[
0 = c^2 - 21c
\]
Factoring out \(c\) gives:
\[
c(c - 21) = 0
\]
Step 4: Solve for \(c\)
Setting each factor to zero, we find:
\[
c = 0 \quad \text{or} \quad c = 21
\]
Since we are looking for valid solutions, we check both values in the original equation. The valid solution is:
\[
c = 21
\]
Final Answer
The solution to the equation is:
\[
\boxed{c = 21}
\]