Ihave absolutely no idea how to do this and chemistry is my worst subject

1 - 2 NaBr + Ca(OH)2 -> CaBr2 + 2NaOH [Double Replacement]. To balance this equation, look at the subscripts for each element. You can see that Hydroxide and Bromine both are not balanced, so you need to balance them. In order to do this, set up a table with reactants on one side and the products on the other. See the image posted.

2 - 2NH3 + H2SO4 -> (NH4)2SO4 [Synthesis]. Both reactants merge to form one product, thus being synthesis. There needs to be a coefficient of 2 in front of NH3 in order to balance the equation.

3 - 4C5H9O + 27O2 -> 20CO2 + 18 H2O [Combustion]. This is because the reactants produce Carbon Dioxide and water.

4 - 3Pb + 2H3PO4 -> 3H2 + Pb3(PO4)2 [Single Replacement]. This is because Hydrogen was replaced by Lead.

5 - Li3N + 3NH4No3 -> 3LiNo3 + (NH4)3N [Double Replacement].

Hope this helps!