I will show all the steps to lead to the solution.
1) 10b = 5 (√c + 2) <---- starting equation
2) divide by 5 => 2 b = √c + 2
3) subtract 2 => 2b - 2 = √c
4) raise to the power 2 => (2b - 2)^2 = c, which is the expression given.
Now these are two equivalent forms:
1) extract 2 from the parentheses: c = 4 (b -1)^2
2) expand the parentheses: c = 4b^2 - 8b + 4)
