Answer:
Time:
Car > Truck > Boat.
Cost of produce:
Truck > Boat > Car
Profit
Car > Truck > Boat.
We know that a worker works 400 minutes each day, and the profit that each worker needs to generate is $35, let's find how each worker needs to spend their time.
Let's call T to the number of trucks he makes, C for cars and B for boats.
Then, if he works 400 minutes we have:
T*10 + C*12 + B*8 ≤ 400
this means that the time expended crafting the toys can be, at most, 400 minutes (here you use the inequality because the worker actually can be less effective than the max, maybe tacking a break or something like that)
The other equation is:
T*1 + C*1.5 + B*0.6 ≥ 35
Here we use the inequality because the profit needs to be at least 35$, none the less, the profit can be more than tath.
Notice that if we want to solve the system with for the equal signs, it is:
T*1 + C*1.5 + B*0.6 = 35
T*10 + C*12 + B*8 = 400
We have 3 variables and 2 equations, this means that there are more than one solution for this system.
