Solving a value mixture problem using a system of linear equations

two mechanics worked on a car. the first mechanic worked for 20 hours, and the second mechanic worked for 5 hours. together they charged a total of $2125 what was the rate charged per hour by each mechanic if the sum of the two rates was $140 per hour?

Atype of plant is introduced into an ecosystem and quickly begins to take over. a scientist counts the number of plants after mmonths and develops the equation p(m)= 19.3(1.089)^m to model the situation. most recently, the scientist counted 138 plants.assuming there are no limiting factors to the growth of the plants, about how many months have passed since the plants werefirst introduced? a)o 6.1b)0.6.6c)10 72d)o 23.1