The percent decrease in sold can be calculated using the formula:
$$ \text{Percent Decrease} = \dfrac{\text{Original Value} - \text{Final Value}}{\text{Original Value}} \times 100 $$
In this case, the original value is 60 (the number of magazines sold initially), and the final value is 21 (the number of magazines sold now).
Substituting these values into the formula, we get:
$$\text{Percent Decrease} = \dfrac{60 - 21}{60} \times 100 $$
$$ = \dfrac{39}{60} \times 100 $$
$$ \approx 65% $$
Therefore, the percent decrease in magazine sold is approximately 65%.