Hello!

To better illustrate the problem, we will try to enumerate the different types of reaction.

1. Combustion - reaction with oxygen to form Carbon dioxide and water

2. Synthesis - two or more simple compounds joined together to form a more complicated compound.

                   A + B  ---> AB

3. Decomposition- opposite of synthesis reaction.

                   AB -----> A + B

4. Single - one element displace/replace an element in a compound

                   AB   + C    ---->  AC

5. double - it is a switching places of ions during reaction.

                  AB  +  CD   ----> AD  + CB

6. Acid base - a type of double replacement wherein H+ and OH- is involved. Salts are formed in this type of reaction.

                 HCl  + NaOH  ----->   NaCL  + H2O

By inspection we can see that:

ZnBr2 (aq) + 2AgNO3 (aq) -->Zn(NO3)2 (aq) + 2AgBr (s)

is a double displacement reaction. We can also call this as precipitation reaction since AgBr precipitates in the reaction (it is denoted by a letter (s) in the chemical reaction).

KBr (aq) + AgNo3 (aq) --> AgBr (s) + KNO3

similarly, this is also a double replacement reaction/precipitation reaction.

hope this helps :)