But pb = p × b, and rb , = r × b.
qc q c sc s c

Therefore (m + n)a, or

(p + r) b = p × b + r × b.
q s c q c s c

In a similar manner the same may be proved of any other formula.

The following examples may be useful:

a × c + e × g = acfh + bdeg
b d f h
—————————————
a × e + c × gaedh + bcfg
b f d h
1 = b
1 ab + 1
a + —
b
1 = 1 = bc + 1
————————————————————
1 cabc + a + c
a +———— a +———
1 bc + 1
b +—
c

Thus,

1 = 1 = 57
—————————————————
1 8350
6 +———— 6 +——
1 57
7 +—
8