Explanation:
phukan = x
Nanwan = y
let this be a simultaneous equation.
x - y = 18.... equation i
x + y = 100.... equation ii
subtract equation i from equation ii
= 2y = 118
y = 59
substitute y = 59 in equation ii to get x
x + 59 = 100
x = 100- 59
x = 41
Nanwan = 59, Phukan = 41