What is 5d=470 and what is 8a=47

5d=470:

in this case we have to divide both sides by 5:

d=94

8a=47:

in this case we have to divide both sides by 8:

a=5.875

as a general rule, if you want to find out a value of a in
ab=c

you have to divide both sides of the equation by b (if it's not zero); then you will have left:

a=c/b

and if you calculate c/b, this will give you the answer