Ahmad had $160 more than Billy.
Ahmad gave 20% of his money to Billy.
Billy then gave half of his money to AHmad.
In the end, Ahmad had $180 more than BIlly.
How much did Billy have in the end?
Let what Billy had ==B
Ahmad had ==B + 160
Ahmad gave ==0.20[B + 160]==0.20B + 32
B + 0.2B + 32 ==1.2B + 32 - what Billy got.
0.50[1.2B + 32]==0.6B + 16 - what Billy had left
[B + 160] - [0.2B + 32] + [0.6B + 16]==180 + 0.6B + 16
1.4B + 144 ==180 + 0.6B + 16, solve for B
B==65 - what Billy started with.
65 + 160 ==225 - what Ahmad started with.
0.6B + 16 ==39 + 16 ==55 - What Billy ended up with.
1.4B + 144 ==91 + 144 ==235 - What Ahmad ended up with.
235 - 55 ==180 - difference in what they ended up with.
