Answer:
The brother would be 13
Step-by-step explanation:
14 - 6= 8
There's an 8-year difference
21 - 8= 13
Answer:
114.24°
Step-by-step explanation:
7(15)+6= 105
3(15)= 45, now we plug it in the formula, 

so now we square root it
= 114.24
In order to determine volume you should multiple w*d*h. So in this case 5*6*3 or 90 cubic meters.
There’s this website you can search on your phone/laptop called Desmos