, 2023

Since the average of $a$,
$b$ and $c$ is 16, then $\dfrac{a+b+c}{3} = 16$ and so $a+b+c=3 \times 16 = 48$.

Since the average of $c$, $d$ and $e$ is 26, then $\dfrac{c+d+e}{3} = 26$ and so $c+d+e=3 \times 26 = 78$.

Since the average of $a$, $b$, $c$, $d$, and $e$ is 20, then $\dfrac{a+b+c+d+e}{5} = 20$.

Thus, $a+b+c+d+e = 5 $\times$ 20 =
100$.

We note that $$(a+b+c)+(c+d+e) = (a+b+c+d+e) + c$$ and so $48 + 78 = 100 +
c$which gives$c = 126 - 100 =
26$.