4o + 5a = 2
3o + 4a = 1.56
You can solve by elimination or substitution, I prefer elimination.
On a problem like this you are going to have to multiply both equations to either eliminate the x terms or y terms. I'm going to get rid of the x's just because that's what I usually do.
So
-3(4o + 5a = 2)
4(3o + 4a = 1.56)
Now you have:
-12o -15a = -6
12 o + 16 a = 6.24
Add straight down and you are left with
1a = .24
So apples cost 0.24
Now substitute this into one of the original equations and solve for the cost of the oranges. I'll use the first equation
4o + 5(.24) = 2
4o + 1.2 = 2
4o = .8
o = .2
So oranges cost 0.20