Let:
x = cost of the small package of gum
y = cost of the large package of gum
Together, one small package of gum and one large package of gum cost $1.10, so:

If you bought two small packages of gum and one large package of gum, they would cost $1.45. so:

Let:

one small package of gum costs $0.35 and one large package of gum costs $0.75