Question

If tan 72=12/X find X

Answer 1

Multiply 72 by 12 and you'll get your answer

Answer 2

72= 12/x
12/x=72
12=72x
get rid of the fractions in 12/x=72 by multiplying both sides by the lowest common denominator 
72x=12
move factors not having x from the left side of the equation
 
so X= 1/6