Question

Which table has a constant of proportionality between y and x of 0.3

Answer 1

when you multiply the x number in the table c by 0.3 you get the same answer as the one in the y column. The constant of proportionality  is the value that stays constant in the ratio. Since when you multiply each number in the x column by 0.3 and you always get the number in the y column it shows that the table c is correct.