A is the point with coordinates (4, 6) B is the point with coordinates (d, 21)

The gradient of the line AB is three.

Work out the value of d.

The gradient is the slope.

Slope is the change in y over the change in x.

3 = (21-6) / (d-4)

Simplify:

3 = 15/(d-4)

(D-4) = 15/3

D-4 = 5

Add 4 to both sides :

D = 9

step-by-step explanation:

because 1/3 is a fraction. we can tell because there is a divisor symbol between the 1 and the 3. if we were to add 2 fractions together, we would add the numerators, which is the number on top, but not the denominators, which is the number on the bottom

1/3+1/3=2/3

hope this !