#### Answer

$(a)~48\times 3.2\times 0.075\div 190-2\times 0.015$
$(b)~0.031$

#### Work Step by Step

(a)
We are given the formula:
BAC=number of oz$\times\%alcohol\times 0.075\div$body weight in lb-hr of drinking $\times \mathrm{O}.015$
We plug in the values given:
$=48\times 3.2\times 0.075\div 190-2\times 0.015$
(b)
We evaluate using order of operations:
$48\times 3.2\times 0.075\div 190-2\times 0.015$
First we multiply:
$=153.6\times 0.075\div 190-2\times 0.015$
And multiply again:
$=11.52\div 190-2\times 0.015$
Next we divide:
$=0.061-2\times 0.015$
And multiply:
$=0.061-0.03$
And subtract:
$=0.031$