≈alguien me explica las ecuaciones integrales 2 bachillerato, porfa

Which of the following are parts of a sphere

Miranda is braiding her hair.then she will attach beads to the braid.she wants 1_3 of the beads to be red.if the greatest number of beads that will fit on the braid is 12,what other fractions could represent the part of the beads that are red?

What is the result of adding the system of equations? 2x+y=4 3x-y=6