Jonas is trying to expand his wardrobe.  He has 20 pairs of socks, 5 pairs of shoes, 10 pairs of pants and 10 t-shirts.  How many pairs of socks does he need to buy to double the number of individual items in his wardrobe?
First, we must recognize that all pairs of shoes and socks are actually two items each, whereas the pants and the t-shirts are individual items. Therefore there are 20*2= <<20*2=40>>40 individual socks in 20 pairs of socks.
Similarly, there are 5*2=<<5*2=10>>10 individual shoes in 5 pairs of shoes.
Therefore, Jonas has 40+10+10+10= <<40+10+10+10=70>>70 individual items in his collection.
To double this number, we perform 70*2=<<70*2=140>>140.
This means we need 140-70=<<140-70=70>>70 new items to double the size.
Since there are 2 individual socks in each pair, we take 70/2= <<70/2=35>>35 new pairs of socks.
#### 35