Answer:
90, 540, and 190
Explanation:
To write an equation or expression for the numbers, first define the variables.
The "first number" is x.
"6 times a first number" is 6x. This is the second number.
"100 more than the first number" is 100+x. This is the third number.
All together, they add to 820.
x+6x+100+x = 820
8x + 100 = 820
8x = 720
x= 90
So the first number is 90. The second number is 6x = 6*90 = 540. The third number is 100+x = 100+90 = 190.