Составьте пропорции из данных чисел 8; 10;16;5;.

Dear aunt marget,thank you for your letter. i was really glad when i saw it in my mailbox. i am really happy for sally that she got medical school. send my best to her.as for your and uncle john's gift for me, that's fantastic. it is just what i needed, thank you. oh, and as for my planning to go to the restaurant, it was successful! my friend had advised me that restaurant. the food was adorable. by the way, we also were given a 30%-discount card, so now we are thinking about visiting it again at the forthcoming weekend. and yes, i celebrated with my friends very well. it was a good day.now i've got to go, me and my classmates are preparing a school project.with love,egor

1) 12-9
Представим 12 в виде (10+2)
    12-9=(10+2)-9=(10-9)+2=1+2=3 т.е. от десятков отнимали единицы
А теперь 12-9 первое число не изменяем, а второе разбиваем так, чтобы удобно было отнять единицы и получить круглое число 10. 
9=2+7
Тогда 12-9=12-(2+7)=12-2-7=10-7=3
2)12-8=(10+2)-8=10-8+2=2+2=4
   12-8=12-(2+6)=12-2-6=10-6=4
3)12-7=(10+2)-7=10-7+2=3+2=5
    12-7=12-(2+5)= 12-2-5=10-5=5
4)12-6=(10+2)-6=10-6+2=4+2=6
    12-6=12-(2+4)=12-2-4=10-4=6
5)12-5=(10+2)-5=10-5+2=5+2=7
    12-5=12-(2+3)=12-2-3=10-3=7
6)12-4=(10+2)-4=10-4+2=6+2=8
    12-4=12-(2+2)=12-2-2=10-2=8