Question

evaluate $15 + x$ when $x = 0$.
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$$\begin{align*}15 + x &= 15 + 0\\\\&= 15\\end{align*}$$

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evaluate $15 + x$ when $x = 1$.
$15 + x = 15 + \square$

Explanation:

Step1: Substitute \( x = 1 \) into the expression

We are given the expression \( 15 + x \) and we need to evaluate it when \( x = 1 \). So we substitute \( x \) with \( 1 \) in the expression, which gives us \( 15 + 1 \). Wait, no, first, let's look at the box. The equation is \( 15 + x = 15 + \square \), and since \( x = 1 \), we substitute \( x \) with \( 1 \) in the blank. So the blank should be \( 1 \) because we replace \( x \) with its value, which is \( 1 \). Then, if we were to find the result, \( 15 + 1 = 16 \), but the question here is filling the blank in \( 15 + x = 15 + \square \) when \( x = 1 \). So the value to put in the square is \( 1 \).

Step1 (rephrased for clarity): Substitute \( x = 1 \)

Given \( x = 1 \), substitute into \( 15 + x \), so \( 15 + x = 15 + 1 \). Thus, the blank is \( 1 \).

Answer:

The value to fill in the square is \( 1 \), so the completed equation is \( 15 + x = 15 + \boldsymbol{1} \) (and if we calculate the result, \( 15 + 1 = 16 \), but the blank here is for the substituted \( x \) value, which is \( 1 \)).