We will use this system of equations to solve this:
l = lollipop
s = strawberry chew

So first of all, let me explain these equations.
4l + 2s = 0.54 means that 4 lollipops and 2 strawberry chews cost $0.54
s = l + 0.03 means a lollipop plus 0.03 equals the cost of a strawberry chew.
Now, let's solve for s.
4l + 2s = 0.54
Subtract 4l from boths sides.
2s = 0.54 - 4l
Divide by 2 on both sides.
s = -2l + 0.27
Substitute.
-2l + 0.27 = l + 0.03
Subtract l from both sides.
-3l + 0.27 = 0.03
Subtract 0.27 from both sides.
-3l = -0.24
Divide by -3 on both sides.
l = .08
.08 + .03 = .11
A strawberry chew costs $0.11