Question

2p q - st - ( 2 st - 9p q )

Answer 1

"minus sign"

Answer 2

2pq - st - (2st - 9pq)
first i distribute the - sign
=2pq -st -2st + 9pq
Well then we notice i have 2 "pq" and 9 "pq" and -1 "st" and -2 "st"
that means i actually have 11 "pq" and -3 "st"
= 11pq -3st

Answer 3

yep =P

Answer 4

thanks