Plug in 4 into the x.
6(4 + 15)
Distribute 6 into 4 and 6 into 15 and multiply.
24 + 90.
Add.
Your answer is 114.
Evaluate 6(x+15) for x = 4. Subst. 4 for x in (x+15): 6(4+15) = 6(19) = 114
