To solve this problem, we will proceed step-by-step:

Step 1: Understanding the problem

The phrase "the difference of 10 and twice a number $y$" translates to:

$10 - 2y$

Here:

• 10 is a constant.
• Twice a number $y$ means $2y$.
• Difference means subtraction.

Thus, the algebraic expression is:

$10 - 2y$

Step 2: Evaluate the expression for $y = 3$

Substitute $y = 3$ into $10 - 2y$:

$10 - 2(3)$

Simplify:

$10 - 6 = 4$

Final Answer:

The expression is $10 - 2y$, and its value when $y = 3$ is 4.

Would you like a more detailed breakdown or clarification on any step?

Here are 5 related questions for practice:

1. Write an expression for "the sum of 5 and three times a number $x$."
2. Evaluate $12 - 4y$ when $y = 2$.
3. Write an expression for "the product of 7 and a number $z$, then subtract 3."
4. If $y = 5$, evaluate $3y + 8$.
5. Translate "twice a number decreased by 9" into an algebraic expression.

Tip: Always identify keywords like sum, difference, product, and twice to accurately translate word problems into algebraic expressions.