To simplify the expression $10d + d - 2d$, let's combine like terms.

1. Combine the $d$-terms: $10d + d - 2d = (10 + 1 - 2)d$ Simplifying inside the parentheses: $10 + 1 - 2 = 9$

2. The simplified expression: $9d$

So, the expression equivalent to $10d + d - 2d$ is $9d$.

Do you have any questions or want more details? Here are 5 related questions:

1. How do you combine like terms in algebraic expressions?
2. What are the rules for adding and subtracting coefficients of variables?
3. How do you simplify an expression with multiple variables?
4. Can you provide an example of simplifying an expression with more than one type of variable?
5. How do you distribute variables in an expression?

Tip: Always combine like terms by adding or subtracting their coefficients to simplify expressions efficiently.