Question

Write as a decimal 200 add three tens add nine hundreds

Answer 1

200 + 3(.10) +9(.010)
200 + .30 + .09
200.30 + .09
200.39
So 200.39 is your answer..

Answer 2

so 200 as a decimal is 200.00
add 3 tens or 3 tens 10 or 30
add 9 hundreds or 9 times 100 or 900 so

200+900+30=1130


if you mean 3 tenths in decimals or 0.3 and
9 hundreths as a demial or 0.09
added to 200 you would get
200.39