Answer:
d = 4[m]
Explanation:
Torque in physics is defined as the product of force by distance. This way you can use the following equation to calculate the torque.
[tex]T=F*d[/tex]
where:
T = torque [N*m]
F = force [N]
d = distance [m]
Now replacing in the equation above.
[tex]84=21*d\\\\d= 4[m][/tex]