You can put this solution on YOUR website!
Solve for x:
where y = number of seconds (200) to complete the chemical reaction and x = the temperature, in degrees celcius, at which the reaction occurs. Substitute y = 200
Subtract 200 from both sides.
Multiply through by -1 to ease the process a bit.
Solve the quadratic equation by factoring.
Apply the zero product rule: If a*b = 0, then either a = 0 or b = 0 or both.
So you have two answers, as you would expect from a quadratic equation, but it is reasonable to expect that chemical reactions are more likely to occur at higher temperatures than at lower temperatures, so I think that the answer would be 5 degrees celsius.