Prove that the following set is a dynkin system over <mrow class="MJX-TeXAtom-ORD"> <mi mat

$\frac{5}{7}\times \frac{8}{9}=$?

Express the following rate as a fraction in lowest terms. For example, you would enter an answer of ${\displaystyle \frac{12feet}{5\sec onds}}$ with 12 and fett in the boxes above the fraction bar, then 5 and seconds in the bottom boxes.
RATE: ${\displaystyle 2\frac{1}{2}cmf\text{or}4\frac{1}{4}}$ hours.

Solve ${\displaystyle 9x-7y=10}$ for y. (Use interferes or fractions for any numbers in the expression.)

A central railway freight train leaves a station and travels due north at a speed of 60 mph. One hour later an amtrak passenger train leaves the same station and travels due north on a parallel track at a speed of 80 mph. how long will it take the passenger train to overtake the freight train.

I have the following velocity measurements, where the sign of $V_e$ defines opposing directions of movement in a completely symmetric experimental setting:
$\begin{array}{|llr|}\hline V_e[cm/s]& V_m[cm/s]& \mathrm{\Delta }V[cm/s]\\ 9& 9.38& 0.38\\ 8& 8.491& 0.491\\ 7& 7.482& 0.482\\ 6& 6.502& 0.502\\ 5& 5.726& 0.726\\ 4& 4.499& 0.499\\ 3& 2.021& -0.979\\ 2& 2.34& 0.34\\ 1& 2.018& 1.018\\ 0& 0& 0\\ -1& -0.501& -0.499\\ -2& -2.328& 0.328\\ -3& -2.988& -0.012\\ -4& -3.503& -0.497\\ -5& -4.506& -0.494\\ -6& -5.762& -0.238\\ -7& -7.479& 0.479\\ -8& -7.981& -0.019\\ -9& -8.496& -0.504\\ \hline\end{array}$
In this table, $\mathrm{\Delta }V=\left|V_m\right|-\left|V_e\right|$
Running a Student t-test on $\mathrm{\Delta }V$, we find that the mean does not significantly differ from zero, under a type I error of 5%. From this result, I conclude that $\mathrm{\Delta }V$ is a random error.
The reviewer of my work (I'm an academic student) insists that my method does not account for the direction (i.e. the sign of $V$). That is indeed the case, since my test answers a precise question: Does the measurement method ($V_m$) systematically over/underestimates the true velocity ($||V_e||$)?
Instead, the reviewer uses $\mathrm{\Delta }V=V_m-V_e$ to show that the method significantly overestimates $Ve$, especially when $V_e<0$, using the same t-test. However, I am having trouble finding what specific question such a test answers, and the reviewer's statement is wrong in my opinion.
What is the correct way of defining $\mathrm{\Delta }V$ and discern a systematic measurement error?

Determine the lowest common multiple of each of the following list of numbers
a) 9;6
b) 8; 14
c) 2; 9; 54;

The exponential equation and approximate the result, correct to 9 decimal places.
a) $3^{(4x-1)}=11$
b) $6^{x+3}=3^x$
To solve for x.