Question

Here is another problem that can also be solved by working backwards.

Answer 1

According to my brain, Maddy picked 6 cucumbers.

Answer 2

Let t be the number of tomatoes and c be the number of cucumbers...

t=2c and c=t-4
 
Using t=2c in c=t-4 gives you:

c=2c-4  subtracting 2c from both sides

-c=-4  dividing both sides by -1

c=4

So Maddy picked 4 cucumbers.