Answer:
12
Step-by-step explanation:
The least common multiple of {6,8,12} is 24. This can be intuitively figured by noting that any multiple of 12 is a multiple of 6 and that 12 is 1.5x larger than 8. That means we only have so multiple 12 by 2 and 8 by 3 for them to be equal. The GCF of {20,42,72} is 2 as the prime factorization of 20 is 2x2x5 and 42 is 2x3x7. That means even without having to check 72 (which is clearly even so 2 is a factor), we know that 2 is the greatest common factor that they could share. So X/Y = 24/2 = 12
Answer:
These opposite angles are called Vertical Angles.
ANSWER
The solution is 
EXPLANATION
We want to solve the simultaneous equations

and
.
We substitute equation (2) in to equation (1), to obtain

This has now become a linear equation in a single variable
.
We solve for x by grouping like terms.


We divide through by negative 3 to get;
.
Hence, the solution is 
Answer: y= -4
Step-by-step explanation: