Can someone explain how to do this asp you

Ageologist had two rocks on a scale that weighed 4.6 kilograms together.rock a was 0.5 of the total weight.how much did rock a weigh?

Afarm that has 4 x 10^2 acres has 1.2 x 10^5 cattle. what is the average number of cattle per acre? write the answer in scientific notation. answere asap

Someone answer this asap for the length, in feet, of a rectangular rug is represented by the expression 5x² + 2x. the width, in feet, is represented by the expression 3x². which expression represents the perimeter, in feet, of the rug? a. 8x² + 2x b. 8x² + 4x c. 16x² + 2x d. 16x² + 4x