42 . 13 - 22 . 5 + 42 . 7 - 15 . 22
= (42 . 13 + 42 . 7) - (22 . 5 + 15 . 22)
= [42 . (13 + 7)] - [22 . (5 + 15)]
= 42 . 20 - 22 . 20= 20 . (42 - 22)
= 20 . 20
= 400
42 . 13 - 22 . 5 + 42 . 7 - 15 . 22
= (42 . 13 + 42 . 7) - (22 . 5 + 15 . 22)
= [42 . (13 + 7)] - [22 . (5 + 15)]
= 42 . 20 - 22 . 20= 20 . (42 - 22)
= 20 . 20
= 400