If n represents a number, then write an expression for a number that is twice n Help please its for algebra class please help thank you a lot like thanks u guys save my day

It’s pre algebra class

Which ordered pair (c, d) is a solution to the given system of linear equations- c+2d=13 -9c-4d=-15

Janet drove 300 miles in 4.5 hours. write an equation to find the rate at which she was traveling

The length of a rectangle is x times the square root of 100. the width is one-half y more than three-halves x. given that the area of the rectangle is 125 cm2, which equation could represent the rectangle in terms of x and y? a) 5xy − 15x = 125 b) 5xy + 15x = 125 c) 15x2 − 5xy = 125 d) 15x2 + 5xy = 125