Hello there!
15 is a term so the first digit in the code is 4.
15-3y is an expression so the second digit in the code is 5
4 5 x x x is the code right now
Now, let's solve the third puzzle:
4(2y-3)-2y=24
8y-12-2y=24
Combine like terms:
6y=36
x=6
4 5 4 x x is the code right now
The next problem:
1/3(12x-3)=7
4x-1=7
4x=8
x=2
4 5 4 2 x is the code right now
Problem 5: I think it's infinite solutions
4 5 4 2 4 is the code!
I hope it is correct! If it isn't, don't report and send me more puzzles! I would love to strain my brain!
Your friend,