What mass of sulfur should be burned to produce 64.0 tonnes of sulfur dioxide?

Mass of SO₂ produced = 64.0 tonnes = 64 × 1,000,000 g = 64,000,000 g

Molar mass of SO₂ = (32.1 + 16.0×2) g/mol = 64.1 g/mol
No. of moles of SO₂ produced = (64,000,000 g) / (64.1 g/mol) = 64,000,000/64.1 mol

S + O₂ → SO₂
OR: Mole ratio S : SO₂ = 1 : 1
No. of moles of S needed = 64,000,000/64.1 mol

Molar mass of S = 32.1 g/mol
Mass of S needed = (32.1 g/mol) × (64,000,000/64.1 mol) = 32,000,000 g = 32.0 tonnes

Write a bal. equation
S + O2 --> SO2 <<< notice it is balanced with all coeff. = 1 ...

next (998.4 mole SO2) X (1 mole S / 1mole SO2) X (32.1 g S / 1mole S)
. . . . . . (given in moles) X (mole ratio from Bal. Eq) X (molar mass of unknown) ... notice how things cancel .. leaves grams S <<< mass of sulfur ... ... use a calculator
this method gives grams as the mass answer ... if you need tonnes you will need to to another step to convert.
... good luck