[DC123]

for the bromination of m-nitrotoluene my book says the bromine adds ortho to the nitro group shouldn't it be meta to the nitro group since nitro is a strong deactivator and methyl is a weak activator

[orgopete]

I agree with your book. The bromine should be directed into o/p positions to the methyl group. Activating groups generally provide a greater directing effect than deactivating groups as the reaction occurs where the aromatic ring can donate electrons.

[DC123]

Alright, thanks I thought it was just whichever group was the strongest activator/deactivator.  But if it was against a strong deactivator and a weak deactivator would the weak one win?

[orgopete]

Alright, thanks I thought it was just whichever group was the strongest activator/deactivator.  But if it was against a strong deactivator and a weak deactivator would the weak one win?

A: yes. The activating group should be thought of as supplying the electrons for the reaction. If you compared the rates of the reaction with one without the deactivating group, it would be slower. Remember, deactivating groups take electrons away from sites in an electrophilic attack.