Book Maths Puzzle Co-ordinate geometry

this is an Ellipses problem but I can't figure it out. Could you please help me.

x^2+4y^2-10x-40y+121=0

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Book Other Question

CAN YOU HELP WITH A PROB I AM NOT ABLE TO SOLVE
9X-7Y+3Z=-48
2X+3Y+4Z=-4
-3X+2Y-5Z=8 A student has grades on three examinations of 76, 80, and 72. What must the student earn on a fourth examination in order to have an average of at least 80?