can someone show me how to figure these literal equation out? I did them before but my teacher said they were incorrect.

Question

Questions~~
Solve the following formula for the variable indicated

9. r = d/t, where r = rate, d = distance, and t = time for d
( I didn’t know how to answer this one in the first place)

10. 3x - y = 10 for y
My answer~
3x-10
3x-10=7x

What my teacher said~~ Please go back and look at the examples at the end of the lesson.
Examples from the lesson~

Ex. Solve d = m for m
V
d = m Isolate the m using the inverse operation of
V division which is multiplication of V.
V(d) = m (V)
V

Ex. Solve P = 2l + 2w for w
P = 2l +
-2l = -2l
P – 2l = 2w
2 2
P – 2l = w
2

Answer 1

9. r = d/t
multiply each side by t ---> d = rt

10.
3x - y = 10
add y to both sides
3x = y + 10
subtract 10 form both sides
3x - 10 = y

strange way of doing equations:

here is how I would do the last e.g.

P = 2l + 2w
P - 2l = 2W -----> I subtracted 2l from both sides
P/2 - l = w -----> I divided each term by 2
or
w = (P - 2l)/2 as another version of the correct answer

Whatever your other e.g. is suppose to mean

Ex. Solve d = m for m
V
d = m Isolate the m using the inverse operation of
V division which is multiplication of V.
V(d) = m (V)
V

I don't have a clue.

Answer 2

So all I have to do for #9 is say "multiply each side by t ---> d = rt"?
I apologize if I'm taking too much of your time but I really appreciate your help