Alan

... there are two d so d² 

Yes, but be clear that when you say "two d" you mean d*d not 2d.

Why is the i on left of the 3 and not on the right?

Only to make it clear that it isn't inside the square root sign.  As long as it is clear it is outside the square root sign it could go on the right.

Group them into lots of 2+5 = 7

There are 161/7 = 23 lots all together.  In each of these 23 lots there are 5 non-mini-vans, so there are 23*5 = 115 vehicles that aren't mini vans.

5d(2 - 3d) → 5d*2 - 5d*3d → 10d - 15d²

Like so:

\(\sqrt{-3}=0+i\sqrt3\)

Under these conditions pressure*volume = constant, so:

p_final*1 = 1.7*3

p_final = 5.1 atm

Do this as follows:

No.  2^1 = 2.  However, 2^0 = 1

geno wrote; "I agree with the answers given (-5), but I don't understand their methods." 

I, too, was puzzled at first.  I wondered if it was a coincidence due to the choice of numbers used or if it was more generally true.  A little analysis shows it is generally true - see below:

. 

Just multiply 28.35 by 2.3