Answer:
x=6
Step-by-step explanation:
side AB is proportional to side XY
side AC is proportional to side XZ
Since we know side AB and side XY are proportional to each other, if we divide side AB by side XY, we can find the size difference...
12 / 4 = 3
The smaller triangle is 3 times smaller than the bigger triangle so we can find side XZ by dividing side AC by 3...
18 / 3 = 6
x = 6