Marcus had 824 marbles and put them equally into 5 bags. How many marbles will be remaining after placing 164 marbles in each bag?

The right answer is, 4.

Step-by-step explanation:

Why:

164x5 = 820

So:

824-820 = 4

check the picture below.

well, the angle at the vertex d is clearly not a right-angle, let's check for the one at the vertex f which does look like,   however if it's indeed, that means ef is perpendicular to df, in which case their slopes will be negative reciprocal of each other.

so the negative reciprocal of the slope of ef is 1, however the slope of df is not 1, is 1/2, so nope, they're not perpendicular lines.