A school fund raiser collected a total amount of money M. 1/7 of M was used for renovating classes. 2/3 of the remaining money was used for laboratory construction. What fraction of M was used for lab

Money used for renovating classes = $\frac{1}{7}M$.

Remainder = $M - \frac{1}{7}M = \frac{6}{7}M$.

Money for laboratory = $\frac{2}{3}$ of the remainder = $\frac{2}{3} \times \frac{6}{7}M = \frac{12}{21}M = \frac{4}{7}M$.