To solve this operation, we need to first convert the mixed fractions to improper fractions.

4 1/2 = 9/2
0.7 = 7/10
1 85/20 = 25/20 + 85/20 = 110/20

Now we can perform the multiplication:

$9/2-7/10$ $110/20$ = $9/2-7/10$ $11/2$ = $(9<em>10-7</em>2)/10$ $11/2$ = $90-14$ / 10 11/2
= 76 / 10 11/2
= 38/5 11/2
= $38<em>11$ / $5</em>2$ = 418 / 10
= 41.8

Therefore, $41/2-0.7$ * $1.85+3/20$ is equal to 41.8.