Instruction: Extract the value of the target attribute from the given product information and output it along with the corresponding source.

Input:
Product title: Lenovo B50-80 15" i3-4005U 4GB 500GB HDD Windows 7 Pro Notebook Laptop Computer
Product description: Lenovo 15.6" - Intel i3-4005U - 4GB RAM -500GB RAM - Windows 7 Pro B50-80 80LT00H6US
Product feature: UPC: 888772512095, Weight: 6.390 lbs
Product brand: Lenovo
Target attributes: Screen Size
Answer: attribute: screen size
value: 15.6"
source: product description