Change the denominator to 12.
Changed to: 6x/12 = 4y/12 = 3z/12.
Then 6x=4y=3z.
Get: z=2x y=3x/2.
Then we get: x-3x/2+6x/3x-3x/2.
= 2-2 times
Your question should be (x-y+3z)/(3x-y).
=(x-3x/2+6x)/(3x-3x/2)
= 1 1/3
You haven't sorted out the topic yet. Here's the calculation method!
The second question can be proved by making it higher! The area of a triangle is the base multiplied by the height and divided by 2. The bisector is perpendicular to both sides at equal distances. So the height is the same, and the bottom is AB and AC, which is not difficult!