Answer:
David should pack 12 apples and 4 bananas
Price of boots is represented as x, price of tennis shoes is represented as y.
x-y=44.38
x+y=196.12
Isolate x. (Or y, if you wanted to)
x=y+44.38
x=196.12-y
Set them equal to each other.
y+44.38=196.12-y
Solve for y. Then plug it in to either of the two original equations to find x.
x=120.24
y=75.86
Note: This is assuming that the boots are more expensive than the tennis shoes. If the tennis shoes are more expensive than the boots, then the prices would be switched. I didn't find this clear in your question.
