Keep heating dry saturated steam and it leaves the saturation line altogether. How far it has gone is its superheat: $\Delta T_{sh} = T - T_{sat}$ — read aloud delta-T-s-h equals T minus T-sat. $T$ is the measured steam temperature in °C, the number the thermowell actually reports. $T_{sat}$ is the saturation temperature at that steam's own pressure, read off the table. And $\Delta T_{sh}$ is a temperature difference, in C° — not a temperature. The delta is doing real work in that symbol.

So this is a two-step question wearing a one-step coat. The subtraction is trivial; choosing what to subtract is the exam. The saturation temperature must be read at the steam's OWN pressure, because a header at 400 kPa and a header at 1,000 kPa boil thirty-six degrees apart. Take the reading from the neighbouring row and your superheat is wrong by exactly that gap, with no warning whatsoever.

Two nuggets worth carrying. A NEGATIVE answer is not an error to hide — it says the sample is below its own boiling point, so you are looking at wet steam or condensate, and quality is the right question instead. And superheated steam is what turbines are fed, because dry steam entering the machine is steam that will not turn to water in the first few stages and chew the blades.