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