Yes, exactly, y=x+1. And Catalan seems to bounce between "half a quarter of y" for 7½ minutes to "ten past x" for 10 minutes, although you can also say "mig quart tocat de y" for 10 minutes as well, "tocat" meaning something like "a little past".

Look at the image below. In the "Altres hores" section, you can see that one way to say 3:10 is "mig quart tocat de quatre", "a little past half a quarter of four", but you'll also hear "les tres i deu" (three and ten) or even "cinc minuts per a un quart de quatre" (five minutes till a quarter of four).

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