1. Balance the chemical equation
2. How many moles of carbon dioxide are produced by 1 mol acetylene?
3. How many moles of acetylene in 20.0 kg?
4. Using your answers for 2. and 3., how many moles of carbon dioxide are produced from 20.0 kg of acetylene?
5. Convert your answer from 4. into mass - the question does not specify the units required for the amount of carbon dioxide (it simply asks "how much"), but I suspect they probably want kilograms.