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, 
(4m + 7n) + (-3m + 12)
First you must combine like terms. In this case there are only one set of like terms:
4m and -3m
(4m - 3m) + 7n + 12
m + 7n + 12
Hope this helped!
~Just a girl in love with Shawn Mendes
<span>Angles on one side of a straight line always add to 180°.
Look at the picture.
a = 180° - 134° = 46°
b = 180° - 130° = 50°
</span><span>In a triangle, the three interior angles always add to 180°.
a + b + c = 180°
c = 180° - (46° + 50°) = 180° - 96° = 84°
x° = 180° - 84° = 96°</span>
<span>We can see that:
x = a + b</span>
Answer:
0.407 because in the others 7 comes before the 0
two other ratios are 3:4 and 3/4