Answer:
x=1.4 or 21/15
Step-by-step explanation:
If the base were 1, then the final value would never change...it would be a constant...
If the base is between zero and one, it is an exponential decay equation, so the final value would continually get smaller and smaller...
Triangle STU is similar to triangle SVW
so
TU ST
------- = ---------- (as you know SV = ST + TV = 12 + 18 = 30)
VW SV
so
TU 12
------- = ----------
40 30
TU = 12 * 40 / 30
TU = 16
answer
16 inches