How do they know what numbers to pick

What is 1/3x5 on anuber line what does it look like on a number line

(10. in the figure, a aabc is drawn tocircumscribe a circle of radius 3 cm ,such thatthe segments bd and dc are respectively oflength 6 cm and 9 cm. find the length ofsides ab and ac.

Using only odd number for numerators write two different subtraction problems that have a difference of 3/4