Question 111350
{{{f(x) = 3x + 3}}} Start with the given function



{{{f(a+1) = 3(a+1) + 3}}} Plug in x=a+1. In other words, replace each x with a+1



{{{f(a+1) = 3a+3 + 3}}} Distribute



{{{f(a+1) = 3a+6}}} Combine like terms