Let's represent the number as �x. The problem can be expressed as an equation:

5��+7=0x+75x=0

For this equation to equal zero, the numerator (5�5x) must be zero. Therefore, the original number is �=0x=0.

The total students in either club (or both) equals the sum of math and science club members minus those in both clubs. Total = Math + Science - Both.

The probability that the interval I contains $2/3$ is $1/3.$ The probability that interval J also contains $2/3$ is $1/3.$ So, the probability that both I and J contain $2/3$ is $(1/3) \cdot (1/3) = 1/9$.