How much would 60 percent of my final grade be

the following grades is what will make up 60 percent of my final grade

100, 88, 57, 75

So the average of 100, 88, 57, 75 is 80.

100 + 88 + 57 + 75 = 320
320/4 = 80

So you're saying that it will make up 60% of your grade.
60% = 0.6

Multiply the average by 0.6 and it will be 48.

60% of your final grade will be 48

The above grades have an average of 80. Multiplying this by .6 (60%) results in 48. Multiplying the rest of your grade by .4 (100% - 60%) and adding that to 48 results in your final grade.

Well, the average of these grades is 80.

60% of your final grade will be 48