Does the three in 3.0 mean

Achemist has 200 ml of a 10% sucrose solution. she adds x ml of a 40% sucrose solution. the percent concentration, y, of the final mixture is given by the rational function: the chemist needs the concentration of the final mixture to be 30%. how many milliliters of the 40% solution should she add to the 10% solution to get this concentration?

What is sin 7x/4 ? i need on this urgent trig

60 2(x + 2) in the diagram, gef and hef are congruent. what is the value of x?