h(x) = 3x - 4
x is the variable
h(x) is the function
h(6) means that the variable has a value of 6. So, we have to replace x with the number 6 and solve.
Replace x = 6 and solve:
h(x) = 3x - 4
h(6) = 3 (6) - 4
h(6) = 3*6 -4
Multiply 3 by 6
h(6)= 18 - 4
subtract 4
h(6) = 14