# Locomotives

## Opening

# Locomotives

This Burlington Northern and Santa Fe (BNSF) Railway locomotive is about 70 feet long.

- Write an expression to describe the length of 3 locomotives in a row, where
*a*represents the length of 1 locomotive. - Evaluate your expression for
*a*= 70.

## Hint:

To evaluate your expression for *a* = 70, you need to replace any occurrence of*a* in your expression with the value 70