If you have limited financial resources, you can also do push-ups every day. This is a comprehensive exercise, which can practice the core control of pectoral muscle, anterior shoulder muscle, triceps brachii muscle and abdominal muscle. Push-ups compare pectoral muscles and narrow push, and compare anterior shoulder muscles.
Another point is that your weight is too light and you probably don't have much fat, so if you want to widen your shoulders (increase your muscles), you must eat more meat and eggs and strive to gain 5 kg a month. The effect is only (personal experience)
Otherwise, it will not only fail to achieve the effect of wide shoulders, but will further reduce weight.
Also, if you have a hunchback, you can do more pull-ups and tighten your back muscles, which is good for you. Pull-ups are mainly practiced to latissimus dorsi, biceps brachii, orbicularis oculi and forearm muscles.
There are several muscles in the back, such as infraspinatus, which can be practiced by paddling (if you have a barbell). The specific method can search Baidu video, because it is not easy to describe in words.
Remember, if you want to gain muscle, you must start by increasing your food intake and eat more foods with high protein, high carbon and high moisture.
Finally, I will give you a link/html/dz _ jsbk _ rtbk/2006-9/20/2006 _ 09 _ 20 _12 _ 01_ 20 _ 06920120.
I wish you success in gaining muscle.