Question

tan 10 - tan 50 + tan 70

Answer 1

to solve tan10+tan70-tan50:
first of all , note all the decimal numbers of given t-ratios.
tan10=0.64 
tan 70=1.22 
tan 50=0.27 

then it would be: 
0.64+1.22-0.27 
=1.59

Answer 2

it would be 1.59 because
 tan10=0.64 
tan 70=1.22 
tan 50=0.27 
                        therefore 0.64-0.27+1.22 
                         =1.59