Вершина это один угол в итоге 6 , 5
Now your brother is 16 and you are 18 :
1) 16×5=80;
18×10=180;
180-80=100.
Ten years ago your brother was 6 and you were 8:
2)8^2=64;
6^2=36;
64+36=100.
So your brother is 16 years old.
3(-2х+1)-2(х+13)=7х-4(1-х)
-6х+3-2х-26=7х-4+4х
-8х-26=11х-4
-19х=19
-х=1
х=-1
6+1+2-26=-7-4-4
-15=-15