A math class has 3 girls and 7 boys in the seventh grade and 3 girls and 3 boys in the eighth grade. The teacher randomly selects a seventh grader and an
eighth grader from the class for a competition. What is the probability that the students she selects are both girls?
Write your answer as a fraction in simplest form.

The decibel level of sound is 50 db greater on a busy street than in a quiet room where the intensity of sound is watt/m2. the level of sound in the quiet room is db, and the intensity of sound in the busy street is watt/m2. use the formula , where is the sound level in decibels, i is the intensity of sound, and is the smallest sound intensity that can be heard by the human ear (roughly equal to watts/m2).

Find the solution of system of equation y= x-4 y=4x+2

Find the greatest common factor of the polynomial: 10x^5+15x^4-25x^3 10x^5 x^3 5x^3 5