Question

suppose a computer processor can perform about 2.3 billion operations per second. how many operations can it perform in 0.7 seconds

Answer 1

1.61 billion/0.7 seconds

Answer 2

2.3bil/1 second= x/0.7 seconds
2.3 billion is to 1 second as x is to 0.7 seconds.

Then you cross multiply.
(1 second)(x) = (2.3 bil)(0.7 seconds)
x= 1.61 billion

Hope this helps!! :)