How do you know w/o calculator? plz

What sums are equal to 6/12? choose all answers that are correct a.6/12+6/12+6/12+6/12+6/12+6/12 b.2/12+1/12+1/12+2/12 c.5/12+1/12 d.1/12+1/12+1/12+3/12 plz : )

Rationalize the denominator- 12x/√x-10

Which of the following circles have their centers in the third quadrant? check all that apply.