I'm not completely positive but I believe this is how you do it.
<span><u />7d - 4d = 21</span>
<span>3d = 21 </span>
<span>3d / 3 = 21 / 3</span>
<span>d = 7</span>
The answer is 7794, rounded is 7790.
Since the 4 in the ones place is not greater than 5, you round down and get 0.
Answer i am not sure wht it is srry