Why does 3x4 and 3x4 the same answer?

The difference of 2 numbers is 21 and the quotient of the equation is 4 then what are the two numbers?

In two or more complete sentences, formulate how to use technology to calculate the appropriate regression model for the given data. you are not required to find the model, just choose the appropriate regression and explain how to use the technology. (-5,,2.,0.8), (0,-0.5), (2,-1.3), (3,-0.8), (5,2)

If f(x)=3x+1 and f^-1=x-1/3, then f^-1(7)=