37 31 - 53 12
= (-------- - ---------) : ------------ + -------- : (-4) =
21 9 42 7
37*3 - 31*7 42 12 111 - 217 42 3
= ------------------ * ----------- - ----------- = --------------- * ----------- - ------- =
63 - 53 7*4 63 -53 7
-106 42 2 * 2 4*7 - 3*3 28 - 9
= ---------- * --------- - 3/7 = ----------- - 3/7 = 4/3 - 3/7 = --------------- = ------------ =
63 -53 3 * 1 21 21
= 19/21