Learn Polish: Szef reaguje mocniej, kiedy maszyna działa wolniej. - The boss reacts more strongly when the machine runs slower.

The basic adverbs are mocno (strongly) and wolno (slowly). For regular adverbs ending in -o, you form the comparative degree by dropping the -o and adding the ending -iej.

Is the letter "n" pronounced differently in wolniej than in wolno?

Yes. Adding the -iej ending softens the consonant before it. Because the n is now followed by an i, it makes a soft sound exactly like the Polish letter ń (similar to the "ny" sound in "canyon"). This happens in both wolniej and mocniej.

Why is the word działa used here for "runs"?

The English word "run" has many meanings, but Polish verbs are more specific. You would use biegać for physical running with legs. For machines, devices, or systems, you must use działać (to function or work).

Can I use gdy instead of kiedy in this sentence?

Absolutely. Both kiedy and gdy mean "when" and can be used interchangeably to connect two parts of a sentence like this.