Once you express one variable in terms of the other using $x - y = 1$, substitute that expression into $2x + 3y = 18$ so that the new equation has only one variable.

After substitution, distribute and combine the $y$-terms correctly. Make sure you add the coefficients of $y$ properly before solving.

After you solve the system, confirm whether the question asks for $x$ or $y$ so you pick the correct value from your work.

In Desmos, type the first equation as 2x + 3y = 18 and the second equation as x - y = 1. Desmos will graph both lines.

Click (or tap) on the point where the two lines intersect. Desmos will display the coordinates of this intersection as $(x, y)$.

Look at the second coordinate of the intersection point (the $y$-value). That number is the value of $y$ that satisfies both equations; match it to the closest answer choice.

Use the simpler equation $x - y = 1$ to solve for $x$ in terms of $y$.

From $x - y = 1$, add $y$ to both sides:

Now you have $x$ written in terms of $y$.

Substitute $x = y + 1$ into the first equation $2x + 3y = 18$.

That gives:

Now simplify this equation.

Distribute and combine like terms in the equation:

Subtract 2 from both sides:

Now you just need to divide to solve for $y$.

Divide both sides of $5y = 16$ by 5:

So the value of $y$ is $\dfrac{16}{5}$, which corresponds to choice C.