To solve the equation 21 + 3x - 2 = 48, we need to isolate the variable x.

First, combine like terms: 21 - 2 = 19.

The equation becomes 19 + 3x = 48.

Next, subtract 19 from both sides of the equation: 19 - 19 + 3x = 48 - 19.

Simplifying further, we have 3x = 29.

To isolate x, divide both sides of the equation by 3: (3x)/3 = 29/3.

The final solution is x = 29/3.