28. A group of tiny organisms (measured in grams) is shrinking at a rate modeled by \( \frac{dM}{dt} = -0.7M \), where the time \( t \) is measured in hours. The size of a second group of organisms decreases at a constant rate of 2 grams per hour according to the linear model \( \frac{dN}{dt} = -2 \). If at time \( t = 0 \), the first group has size \( M(0) = 4 \) and the second colony has size \( N(0) = 6 \), at what time will both groups of organisms be the same size? (Calculator active.)
