Answer:
Alice hit 10 home runs.
Peter hit 8 home runs.
Step-by-step explanation:
Let [tex]p[/tex] be the number of home runs Peter hit.
Let [tex]a[/tex] be the number of home runs Alice hit.
[tex]p=2(a-6)\\a+p=18\\\\a+2(a-6)=18\\a+2a-12=18\\a+2a=30\\3a=30\\a=10\\\\a+p=18\\10+p=18\\p=8\\\\p=2(a-6)\\8=2(10-6)\\8=2(4)\\8=8[/tex]