⊦ i + j = j + i
j0 < j, 0 ≤ i0, 0 < j, 0 ≤ j0, 0 ≤ i1 ⊦ i1 * i0 + (i0 * j0) / j = (j0 * i0 + (i1 * j) * i0) / j
Used terms: j0 * i0, (i1 * j) * i0