6+4×5 = 26 is the answer
Because, number of branch in x-mas tree gives its number,
Number of spikes in steering wheel tells it's number,
Star has value 2.
All these are evident from equations:
3 x-mas+star = 21
=》1 x-mas+star = 7
x-mas tree has 5 stepped branches, so it's value is 5 giving value 2 to star.
In equation 2, substituting known things tells steering wheel value = Number of spikes in side