Unions have generally been far more successful in organizing and raising wages in skilled trades such as carpentry than in unskilled trades. Use the laws of derived demand to explain why

What will be an ideal response?

There are at least two reasons. One is that the elasticity of substitution between skilled workers and other factors of production is low; thus firms cannot substitute some other factor of production if wages rise. Secondly, skilled labor is likely to be a relatively small percentage of total costs, and thus raising wages does not cause a large increase in total costs (which would lead to a reduction in supply, an increase in price, and a decrease in output). Unskilled labor has more substitutes and is likely to be a larger share of costs for firms that employ it, and thus if unions raise wages, firms employ other factors of production, and many workers will be laid off.