I'm not sure if you meant to write 3x or
instead of x3 but I will work out both versions just in case
In the equation 3x + 4 plug 6 in for x
3(6) + 4
Multiply 3 and 6 first
18 + 4
Add 18 and 4
22
OR
In the equation
+ 4 plug 6 in for x
+ 4
Solve the exponent
(6*6*6) + 4
216 + 4
Add the numbers together
220
Hope this helped!