###Human: 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?, ### Assistant: 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= 40 individual socks in 20 pairs of socks.
Similarly, there are 5*2=10 individual shoes in 5 pairs of shoes.
Therefore, Jonas has 40+10+10+10= 70 individual items in his collection.
To double this number, we perform 70*2=140.
This means we need 140-70=70 new items to double the size.
Since there are 2 individual socks in each pair, we take 70/2= 35 new pairs of socks. 
 So the answer is :  35