If you show work I will award brainliest. Only one question in picture.

Answer:
d=7-2/3f
Step-by-step explanation:
Move the variable to the right-hand side and change its sign- 3d=21-2f
Divide both sides of the equation by 3- d=7-2/3f
Write the solution d in parametric form- d=7-2/3f
Solution- d=7-2/3f