Помогите пожалуйста. С лодки массой 40кг, движущейся со скоростью 1м/с, ныряет мальчик массой 40кг, двигаясь с кормы лодки со скоростью 4м/с. Какой станет скорость лодки после прыжка?

125*0:(45*4)+(120*10:100-8)*(15*1000:5)  решите пожалуйста блогодарна буду

составьте текст-рассуждение на тему от чего идёт дождь? Для чего больным ставят градусник?На любую из этих тем!Прошу вас у меня очень мало времени!

Найдите основание равнобедренного треугольника,если угол при основании равен 30 градусов, а  высота, проведенная к основанию,равна 10.

1. If it (rain) this weekend, we (not be able) to go to the country. 2. Give me Ann’s letter. If I (see) her, I (give) it to her. 3. I have to work hard, so I’m very busy. But if I (have) any free time, I (go) in for swimming. 4. If I (be) taller, I (can) play basketball. But I’m too short. 5. Please stop talking! If you (not start) your meal now; it (go) cold. 6. If you (have) any problems, let me know and I (help) you. 7. You’re a wonderful cook! If I (can) cook as well as you, I (open) a restaurant. 8. We must hurry! If he (be) late, we (leave) without him. 9. He (have) a day off tomorrow if he (work) hard today? 10. That coat looks awful! I (not buy) it if I (be) you. 11. I think there are too many cars. If there (not be) so many cars, there (not be) so much pollution. 12. It’s a pity I’m not rich. If I (be) rich, I (have) a yacht. 13. I’m going out now. If anybody (phone) while I (be) out, can you take a message? 14. This soup isn’t very good. It (taste) better if it (not be) so salty. 15. ‘What shall we do tomorrow?’ ‘Well, if it (be) a nice day, we (not stay) at home.’ 16. Liz is tired all the time. If she (not go) to bed so late, she (not be) tired. 17. You were rude to Mike. If I (be) you, I (apologize). 18. We’re lost. If we (have) the map with us, we (know) where we are. 19. If I still (feel) sick, I (not go) on holiday next weekend. 20. I don’t get any help at work. My job (be) easier if I (have) a secretary.