Answer:
$160
Step-by-step explanation:
I = 800 * 5 * 4% (I multiply the time and principal first, so I already have the wholes covered.)
I = 4,000 * 4% (now to convert 4% and 4000 into fractions.)
I = 4000/1 * 1/25 (Cross cancel if needed. GCF is 25.)
I = 160/1 * 1/1 (Just remove 1/1)
I = $160 (There's your answer!)