Please help and explain the steps have been stuck for a while now :(

Road Angle Trucks recently investigated a design deficiency in the assembly of an engine of their newly launched vehicle RT-3. Truck drivers reported that the assembly had failed, causing fuel leakage and serious fire damage to the vehicle engine and engine compartment. There were instances where the fire spread outside the engine compartment and destroyed the entire vehicle. In each instance, the driver had ample time to evacuate the vehicle. Road Angle Trucks found two possible solutions to reduce or eliminate the fuel leakage problem. The first is a new engine with a modified block and assembly that eliminates the fuel leakage problem. A second solution is a field modification to the existing head assemblies accomplished at their maintenance units. After a careful initial investigation, the solution team has provided the summary of their investigation listed below: i. In case of continuing to use the vehicles in their present condition: The analysis based on the on-hand data indicates that the probability of "fuel leakage and fire" is 0.2. In Addition to that, the analysis indicates that when there is a "fuel leakage and fire", 90% of the time the damage is confined to the engine compartment and the repair cost is $200,000. Otherwise, the damage can destroy the entire vehicle. The replacement cost is about $1,300,000.ii. In case of replacing all the engines with brand new engines: The new engines should not manifest this particular problem but the replacement of existing engines will cost $100,000 each. 111. In case of making a minor modification to the existing "head assemblies": Engineers estimate that this modification would cut the probability of "fuel leakage and fire" in half. If the modified assembly fails, the results are the same as with the old assembly. This modification will be at a cost of $30,000 per head assembly. Draw a decision tree for this problem to help Road Angle Trucks make the best decision. Solve the decision tree and determine the decision strategy that Road Angle Trucks should follow and its minimum expected cost. (Show your work/calculations). Verbally communicate the decision strategy (30 points)