Answer:
The two main variables in an experiment are the independent and dependent variable. An independent variable is the variable that is changed or controlled in a scientific experiment to test the effects on the dependent variable. A dependent variable is the variable being tested and measured in a scientific experiment.
When you take blood pressure, it is expressed in a fraction. The top number of that fraction is systolic pressure- the amount of pressure in your arteries during contraction of your heart muscle... I hope this helped! :)