The sum of two decimal numbers is 3.9. Their difference is 0.9, and their product is 3.6. What are the two numbers?
the two numbers are 1.5 and 2.4
a+b=3.9
a-b=0.9
a=0.9-b
subbing in the second formula into the first
0.9+b+b=3.9
2b=3.0
b=1.5
a+1.5=3.9
a=2.4