What is the branch of mathematics that uses letters and other general symbols to represent numbers and unknown Quantities

Atheater wants to build movable steps that they can use to go on and off the stage. they want the steps to have enough space inside so they can also be used to store props. how much space is inside the steps?

Guys can y’all me because i don’t understand to the questions of my cousin she tell me to do the homework plz me guys

Abuilder divides a rectangular plot in half along the diagonal.if the plot is 1\2-mile wde and the diagonal measures 1 3\10-miles long,what is the length of the plot?