$122 because if you add 55 + 67 you get 122 then you just add the dollar sign
135 mg*1g/1000mg*10dg/1g=1.35 dg
The first expression can be simplified by combining like terms.
First, the terms "4b" and "-3b" can be combined to form "b"
Then, the terms "-7" and "9" can be combined to form "2"
Finally, we simply put these two final terms together, to form "b+2"
Hence, 4b-7-3b+9 is equal to be + 2.
Hope this helps!
The sale is 33% off notebooks. This can be found by first subtracting .8 from 1.2
1.2-.8=.4 Now divide .4 by 1.2 to get your answer.

=.33
.33=33%
You can also solve this mentally because if you know your basic multiplication tables, 3*4=12 and so

of 12 would equal 8.
Does you understand it now?