Question

solve these problems

Answer 1

$3mn + ( - 5mn) + 8mn - 4mn$
$3mn - 5mn + 8mn - 4mn$
Using BODMAS rule
$11mn - 5mn - 4mn$
$11mn - 9mn$
$2mn$
This was your first sum.
Now you can solve others with same method.

For more help I will only do 2nd part.
$t - 8tz + 3tz - z + z - t$
Combine Like terms
$t - t - 8tz + 3tz - z + z$
$- 8tz + 3tz$
$- 5tz$
These are interesting. So I will do more.
here is 5th part
$14x + 10y - 12xy - 13 + (18 - 7xy - 10y + 8xy) + 4xy$
$14x + 10y - 12xy -13 + 18 - 7x - 10y + 8xy + 4xy$
Now you can solve it easily by seeing above easily.

Mark as brainliest, the task is really worth of cost.