Question

Jack usually mows his lawn in 7 hours. Marilyn can now the same yard in 6 hours. How much time would it take for them to mow the lawn together?

Answer 1

solve
\[(\frac{1}{7}+\frac{1}{6})t=1\]
\[(\frac{6+7}{6\times 7})t=1\]
\[t=\frac{6\times 7}{6+7}\]