I see! Thank you

I’m stupid, can someone help me understand how we calculate the 18 point swing?

Just after Trump was inaugurated last February, the result was 58 percent saying Trump was doing a better job than Biden

But in the new poll, 51 percent said Trump is doing a worse job than President Biden did — a net swing of 18 points

2025 poll 58% say Trump > Biden

2026 poll 49% say Trump > Biden (aka 100 - 51)

58-49 = 9 point swing?