suppose that there is three angle in this triangle and they were named a,b,and c
now given that
a+b=118 equation 1
and a-b=32 equation 2
by equation 1
a=118-b
now put the value of a in equation 2
(118-b)-b=32
118-b-b=32
2b=118-32
b=86/2
b=43
now put the value of b in equation 1
a+43=118
a =118-43
a=75
now we knows that
a+b+c= 180
75+43+c=180
118+c=180
c=180-118
c=62
