The total number of red counters that are in the box is; 728 red counters
Let the number of white counters be x.
Let the number of red counters be y.
Let the number of black counters be z.
Thus;
z:x = 2:7
Thus; 2x/7 = z
Also, we are given;
x:y = 3:8
Thus;
8x/3 = y
x + y + z = 1079
x + (8x/3) + (2x/7) = 1079
Multiply through by 21 to get;
21x + 56x + 6x = 22659
83x = 22659
x = 22659/83
x = 273
2x/7 = z
Thus; z = 2 × 273/7
z = 78
8x/3 = y
y = 8 × 273/3
y = 728
273 white counters
728 red counters
78 black counters.
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