Question

simplify
I12-21I
12-21
=-9
is that correct

Answer 1

not quite.
| 12 - 21 |
simplify inside abs value bars first
| -9 |
then apply abs value rule: how far is the number from zero?
since -9 is 9 units away from zero, the abs.value of -9 is 9!!

Answer 2

of so i was close instead of -9 it 9