A light truck is purchased on January 1 at a cost of $19,000. It is expected to serve for five years and have a salvage value of $1,000. Calculate the depreciation expense for the first and third years of the truck's life using the following methods:

Question

A light truck is purchased on January 1 at a cost of $19,000. It is expected to serve for five years and have a salvage value of $1,000. Calculate the depreciation expense for the first and third years of the truck's life using the following methods: 
Depreciation Expense 
                         Year 1 Year 3 
1.Straight-line          3600   3600  
2.Double-declining-balance   $  $  
3.Sum-of-the-years'-digits   $  $

I have tried the examples in my book but I am not getting the correct solution. I want to understand what I am doing from start to finish because I have a whole chapter on depreciation. Please help.