40%
The probability of her getting a red marble is the number of red marbles divided by the number of total marbles. Since she picked a green marble first, we must subtract one marble from the total number of marbles, so that the total # of marbles is 6 + 6 + 4 = 16 - 1 (green marble) = 15. Since there are 6 red marbles, our probability is 6/15 or 2/5. Converted to percentage form, this is 0.4 —> 40%
3t+12-4t-6=-4
-t=-4+6-12
-t=-10
t=10
That's your answer.
