Answer:
Peter is 20 years old
Step-by-step explanation:
John= 2(Peter's age) (j=2p)
Peter= (Alice's age + 5) (P= A+5)
Okay, so let's substitute the equations now:
John= 2(Alice + 5)
So the equation for 5 years from now is:
2(A+5) + 5 = 3a (because he is 3 times as old as alice)
so, let's solve for that equation:
2a + 10 + 5 = 3a
subtract 2a from both sides:
15= a
so, Alice is going to be 15 years old, so now we can solve for Peter's age:
P= A + 5
P= 15 + 5
P = 20
Peter is 20 years old
I hope this helps! :)