What is the value of x and y?
I. 3x + 2y = 45
II. 10.5x + 7y = 157.5

Considering first statement alone, 
As there are 2 variables x and y, and one equation we can't say anything absolute about values of x and y.
Considering second statement alone,
With 2 variables and one equation, we can't say anything absolute about variables x and y.
Even considering both statements together, we can't find values of x and y as equation in 2nd statement is same as in 1st statement after multiplying it 3.5