5t[t-(r-s)]

Question

trouble with grouping symbols

Answer 1

This is just an order of operations question.  PEMDAS

5t[t-(r-s)]

Start with the inner-most parentheses:

5t[t-r+s]      you can think of -(r-s) as (-1)(r-s)

Now expand the remaining expression:

(5t)(t) - (5t)(r) + (5t)(s)

5t²-5rt+5st