Question 105575
ans.:

{{{31C - 49C =18 H}}}

to understand it, you just make number line where {{{C}}} represents negative numbers and {{{H}}} represents positive numbers:


{{{-31}}},{{{-30}}},{{{-29}}}{{{......}}}{{{-1}}},{{{ 0}}}, {{{1}}},{{{.....}}}{{{17}}},{{{18}}},{{{19}}}.....

if you go from {{{-31}}} to the right {{{49}}}units, you will end at the position of the number {{{18}}}