217•35-215•36

To calculate \( 217 \times 35 - 215 \times 36 \), we can simplify the expression.

We can rewrite the expression using the distributive property:

\[ 217 \times 35 - 215 \times 36 = 217 \times 35 - 215 \times (35 + 1) \]

This simplifies to:

\[ 217 \times 35 - 215 \times 35 - 215 \]

Now we can factor out \( 35 \):

\[ (217 - 215) \times 35 - 215 = 2 \times 35 - 215 \]

Calculating the multiplication:

\[ 2 \times 35 = 70 \]

Now substitute back:

\[ 70 - 215 = -145 \]

Thus, the final result is:

\[ \boxed{-145} \]