This involves another of the secant rules for circles. When chords divide each other, the product of the segment lengths of one chord is equal to the product of segment lengths of the other chord.
18·6 = 9·YB
18·6/9 = YB = 12
I'm not 100% sure what the question wants as its answer, but having a class of 26 students is around the average number of students in a class.
2x=y where 2 is dollars per tomatoe, x is amount of pounds of tomatoes, and y is amount of money spent in total. say you got 3 pounds of tomatoes; the equation would be 2(3)=y. y=6. Hope I helped!