Im in this same class, although Im not gonna give you the answer I'll give some hints.
First a few errors in your coding:
The Store command is STA not STO
You have to number all your code lines starting with 00
EX. 00 IN
You only have 2 inputs for the first part, so you cant read in 3 times.
Now some hints:
Try subtracting the second number that was stored from the first number then restoring in the same slot. Then use the SKN coupled with the JMP command to reiterate your code...like a loop. That way it will keep subtracting until it hits negative, and dont forget to output each number.
For the Triangle one the area is 1/2(base * Height) just think about what multiplication is in Addition. (Use a counter). The first part is to get you ready for the second part, remember that. For division the dividing factor is by two so use a counter like in multiplication but subtract the numbers instead of add and deduct from the counter by 2 instead of 1.