Answer:
The tonicity of a solution depends on the concentration of solutes in the solution.
In this case, 3.3% dextrose + 0.3% NaCl can be thought of as being the same as 0.9% NaCl, which is isotonic.
5% dextrose + 0.3% NaCl is hypotonic, because the concentration of solutes is lower than that of the intracellular fluid.
3.3% dextrose + 0.9% NaCl is hypertonic, because the concentration of solutes is higher than that of the intracellular fluid.
Therefore, 3.3% dextrose + 0.3% NaCl can be thought of as being the same as 0.9% NaCl, which is isotonic.