find k - the constant of proportionality. y = kx k =

Explanation:

Step1: Use the formula ( y = kx )

Rearrange to ( k=\frac{y}{x} ).

Step2: Substitute values from the table

Take ( x = 5,y = 10 ). Then ( k=\frac{10}{5} ).

Step3: Calculate

( k = 2 ). Check with other values: for ( x = 15,y = 30 ), ( k=\frac{30}{15}=2 ); for ( x = 25,y = 50 ), ( k=\frac{50}{25}=2 ).

Answer:

( 2 )