Which expression is equivalent to 5x+3?

a. 8x
b. 3+5x
c. 3x+5
d. 5(x+3)

Jack has a piece of red ribbon that is two times as long as his piece of blue ribbon. he says that he can use two different equation to find out how long his piece of red ribbon is compared to his piece of blue ribbon is. is he correct? explain his reasoning

The area of a rectangle is 10 cm^2. one side of the rectangle is x cm. express the perimeter of the rectangle in terms of x and show that this rectangle cannot have a perimeter of 12 cm. the perimeter of the rectangle in terms of x is __ cm

An elevator travels 310 feet in 10 seconds. at that speed, how far can't his elevator travel in 12 seconds?