What does semicolon mean in math

Emma will roll two number cubes labeled 1 through 6. she will record the sum of the two numbers after each roll. she will roll the two cubes 540 times. how many times should emma expect the sum to equal 5?

What number should be added to the expression x^2+3x+ in order to create a perfect square trinomial? 3/2 3 9/4 9

The trigonometric ratios sine and secant are reciprocals of each other