To solve for \( j \) in the equation \( 4.3 = \frac{j}{3} \), you can start by multiplying both sides of the equation by 3 to isolate \( j \):
\[ 4.3 \times 3 = j \]
Now, calculate \( 4.3 \times 3 \):
\[ 4.3 \times 3 = 12.9 \]
So,
\[ j = 12.9 \]
Thus, the solution is:
\[ j = 12.9 \]