Here's how to calculate the number of moles of MgS2O3 in 215 g:

1. Find the molar mass of MgS2O3:

* Mg: 24.31 g/mol

* S: 32.06 g/mol (x2 for two sulfur atoms)

* O: 16.00 g/mol (x3 for three oxygen atoms)

Molar mass of MgS2O3 = 24.31 + (32.06 x 2) + (16.00 x 3) = 136.43 g/mol

2. Use the formula: moles = mass / molar mass

moles of MgS2O3 = 215 g / 136.43 g/mol

= 1.57 moles

Therefore, there are approximately 1.57 moles of MgS2O3 in 215 g of the compound.