Answer:
a+b=5/2a, a+b=5/3b
Step-by-step explanation:
1.2a=0.8b
6/5a=4/5b
6a=4b
b=3/2a, a=2/3b
a+b=3/2a+a
a+b=5/2a
a+b=2/3b+b=5/3b