Answer: 60 hours.
Step-by-step explanation:
Let be "x" the amount of hours Nick practice in March and "y" the amount of hours Nick plans to practice in April.
Set up a system of equations:
[tex]\left \{ {{x=42} \atop {y=x+18}} \right.[/tex]
Applying the Substitution Method, we can substitute the first equation into the second equation in order to find the value of "y". Therefore you get this result:
[tex]y=x+18\\\\y=(42)+18\\\\y=60[/tex]