For those kinds of question assume a certain value ( the original production).
Then account for the new production value.
Take the difference between the new and the original production.
Assume orig. prod.= 100
100 * 1,1 * 1,2 = 132
132 - 100 = 32
That's the percentage the new production has to be decreased in order to restore the original production
Sure, we have to make another step.
132 * x/100 = 100