Answer:
a=2(s-5)
a(your age): 20
Step-by-step explanation:
a stands for your age
s stands for sister
a=2(s-5)
1-substitute 15 for s a=2(15-5)
2- a=2(10)
the 15-5 stands for sisters age minus five which gives you brothers age, 10. You multiply it by two because your brother is half your age.
3-a=20
check your work:
because your brother is 10 and you are 20, he is half your age (10/20 can be simplified to 1/2)
Hope this helped, if you have any other questions please lmk!