Answer :
a+b=86
a-b=6
a=86-b
substitute: 86-b-b=6
-2b=-80
b=40 and a=46
a-b=6
a=86-b
substitute: 86-b-b=6
-2b=-80
b=40 and a=46
40 + 46 = 86
because...
c = 86
a - b = 6
46 - 40 = 6
a + b = c
46 + 40 = 86
because...
c = 86
a - b = 6
46 - 40 = 6
a + b = c
46 + 40 = 86
