It is false. Since you don't know what is the variable equal to. But multiplication can't be in associative property.
Let's begin by listing out the information given to us:
We start out by observing that Triangles MKR & ACD are similar or proportional

We will solve for the missing side by using the similar triangle theorem. This is shown below:~
Focus on triangles DFC and DFE:
- They are both right triangles because DF is perpendicular to EC
So, the two triangles are congruent. It follows that CF=FE, and in particular

And since x=3, the length of EF is

Answer:
3,000 words
Step-by-step explanation:
we know that
Emilio cay type 850 words in 17 minutes
Remember that

so
using proportion
Find out how many words can Emilio type in 60 minutes (one hour)
Let
x ---> the number of words

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