Quantity tax and Food Stamps

(a)Consider a two-good (X and Y) model. How does aquantity tax(i.e. per unit tax) ongood Xaffect thebudget line of a consumer?

(b)A country recently passed a food stamp legislation. Qualified households are given food stamps, which can be used to purchase foods, but they cannot legally re-sell them. Suppose a household receives a grant of $300 of food stamps per month. How will this household's budget line be affected? (Hint: Consider two goods: food and other goods.)

Hi, I am really struggling with question B. I have found a previous answer to this question however, I am confused as to why the budget line in there answer is kinked.

Thank you.