Question

does the letter come before the number

Answer 1

In Algebra, the letter comes after the number in the final answer.

So, it would be 5d.

Answer 2

you need to combine like terms. so 2•d•5•d•d•5= 50d^2

multiply left to right so 2•5•5= 50 d•d•d= d^3
you can't combine like terms anymore so 50d^3

i hope this helps