An automatic swing is designed to hold a baby who weighs at least 12 pounds but no more than 20 pounds. If a baby weighs 7.2 pounds at birth and gains 0.2 pounds each week, for what range of weeks will it be safe to put the baby in the swing? Write your answer in interval notation. No spaces!

Question

anonymous · Answer

i think this is a tortured attempt to get you to solve 
$$12\leq 7.2+.2x\leq 20$$

anonymous · Answer

My thoughts exactly and how did you get this?