$X$ is $20 \%$ of 50.40 is $20 \%$ of $Y .40$ is $Z \%$ of 50 . What does $X+Y+Z$ equal?
(A) 218
(B) 335
(C) 98
(D) 290
(E) 380
$X$ is $20 \%$ of 50 , and so $X=0.20 \times 50=10$.

$20 \%$ of 100 is 20 , and so $20 \%$ of 200 is 40 . Thus $Y=200$.

40 is $Z \%$ of 50 , and so $Z=\frac{40}{50} \times 100=80$.

(We may check that $80 \%$ of 50 is indeed $0.80 \times 50=40$.)

Therefore, $X+Y+Z=10+200+80$ or $X+Y+Z=290$.

ANSWER: (D)