Alessandro and Mohammad were playing a math game. Alessandro had 5 points for every 4 points Mohammad had. When Alessandro lost 9 points, He then had half as many points as Mohammed. How many fewer points did Alessandro have than Mohammad?
a/m = 5/4
a-9 = 1/2 m
to make things a bit easier, rewrite it as
4a = 5m
m = 2a-18
so
4a = 5(2a-18)
4a = 10a - 90
a = 15
so m = 12
15-12 = 3