How do you work out the value of "d" in the equation: 7d=4d+21?

17 in long 1.3 ft wide and 8in high what is the volume

Acylinder with a base diameter of x units has a volume of jxcubic units which statements about the cylinder are true? check all that apply. the radius of the cylinder is 2 x units. the radius of the cylinder is 2x units. the area of the cylinder's base is 200 square units. the area of the cylinder's base is a square units. the height of the cylinder is 2x units. the height of the cylinder is 4x units. mark this and return save and exit next submit

Simplify the following expression 48^1/2