To solve each equation for \( x \), we will analyze each option.
A. \( x + 7 = 10 \)
To solve for \( x \): \[ x + 7 = 10 \ x = 10 - 7 \ x = 3 \]
B. \( 3 + x = 3 \)
To solve for \( x \): \[ 3 + x = 3 \ x = 3 - 3 \ x = 0 \]
C. \( x \cdot 3 = 1 \)
To solve for \( x \): \[ x \cdot 3 = 1 \ x = \frac{1}{3} \]
D. \( 4 \cdot x = 12 \)
To solve for \( x \): \[ 4 \cdot x = 12 \ x = \frac{12}{4} \ x = 3 \]
Now, we summarize the solutions:
- A: \( x = 3 \)
- B: \( x = 0 \)
- C: \( x = \frac{1}{3} \)
- D: \( x = 3 \)
The equations that have \( x \) as a solution are A and D (both yield \( x = 3 \)). The other equations have different solutions: B gives \( x = 0 \) and C gives \( x = \frac{1}{3} \).
Thus, the answers are:
- A and D are solutions for \( x = 3 \).