BigBrain

https://en.wikipedia.org/wiki/Chinese_remainder_theorem

Learn it first

May I ask where you got this? And please SEARCH YOUR PRBLEM BEFORE ASKING FOR HELP

We can use the circle equation:$(x-h)^2+(y-k)^2=r^2$,$h=$x of center,$k=$y of the center

so $x^2-2x+y^2=24$ Is now more clearer because if $(h=-1,k=0),(x-1)^2+(y)^2=5^2$simplified is:

The middle:$(-1,0)$, the raidius $r=5$