You would set up a proportion. 3/8 = 6/x... cross multiply ( 3*x = 3x and 6*8 = 48) 3x = 48... divide both sides by 3 (3x/3 = x and 48/3 = 16)
So, she originally had 16 feet of ribbon.
A circle would be the answer
2/5
Since 12 out of 30 marbles were black, you can assume that the percentage of black marbles in the bag is 40% (Ex: 12/30=.4) The probability that the marble you pick is black is equal to the percentage of black marbles in the bag. 40% is equal to 2/5.
The entire race is 1 full race.
One full race is 1.
He ran 3/8 of 1, so he ran 3/8.
He needs to run the rest of the race.
The rest is unknown, so we call it x.
When you add 3/8 to the unknown, you get the full race.
The equation is
x + 3/8 = 1
Change 1 to a denominator of 8.
x + 3/8 = 8/8
Subtract 3/8 from both sides.
x = 5/8
Answer: He still needs to run 5/8 of the race.
