5^n+1-5^n-1/2*5^n упростить выражение

масса однородного кубика равна 800 г. Как изменилась масса кубика если его ребро уменьшилось  в 2 раза

Упростите выражение.

1/x-y  * 1/x-y * ( x/y - y/x)

Помогите пожалуйста!

Complete the text (дополните текст).

The weather (1) ...going to be fine. Our family (2) ...going to spend the holidays in the country. Mother (3) ...going to pick flowers and mushrooms. Father (4) ...going to go fishing. My sister asks, "(5) ...you going to swim? I (6) ...going to go with you!" My friends say, "You (7) ...going to sunbathe. And we (8) ...going to watch TV." They (9) ...going to have fun. And I want to spend the summer in the city and ride my bike but nobody (никто) (10) ...going to listen to me.

Я не понимаю, что сдесь нужно дополнять?