You substitute M for 3 and C for 6. So you get E = (3)(6)(2) which equals 36.
The -1 means that y = -1, so point is one unit below the x-axis. In (5, -1), the x is positive, which could put the point in either the first quadrant or the fourth. With the y being negative, however, it means that the point is in the fourth quadrant. Those are your 2 true statements.
6.76 x 10^11
this is because when you are placing something in a scientific notation you basically move the decimal place behind the last hole number in this case 6. and count the remaining numbers behind the decimal such as .76,000,000,000 which there 11 counting 76 with the zeros. then you place the number of places behind the decimal as an exponent of 11 and keep all real numbers besides 0 as your other half
The answer will be amount of mass in a certain volume .