Parents can't figure out why this math problem was marked wrong

[ahlam1399]

http://img-s-msn-com.akamaized.net/tenant/amp/entityid/AAqQA8R.img?h=100&w=100&m=6&q=60&o=f&l=f&x=443&y=224What do you think?

أكثر... (http://www.msn.com/en-in/lifestyle/relationships/parents-cant-figure-out-why-this-students-math-problem-was-marked-wrong/ar-AAqULpJ?srcref=rss)