The probability for a boy is 8/12 and the girls is 4/12 so that's a 4/12 diffrence
3,100,000
The hundred thousands place is at the sixth digit from the right.
30-f+8f=30
30+7f=30
Move +30 to the right side. Sign changes from +30 to -30.
30-30+7f=30-30
7f=0
Divde by 7
7f/7=0/7
Cross out 7 and 7, divide by 7. Becomes 1*1*f=f
f=0
Answer: f=0
X+7<23
x<23-7
x<16
So, all numbers from zero to 15
Those are 16 positive integers