Question

how do you work out the value of "d" in the equation: 7d=4d+21? 

Answer 1

I'm not completely positive but I believe this is how you do it.

7d=4d+21

7d - 4d = 21

3d = 21

3d / 3 = 21 / 3

d = 7

Answer 2

Subtract 4d from each side. / / / 3d = 21. / / / Divide each side by 3. / / / d = 7 .