Determine whether the triangles are similar

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?

Which of the following pair(s) of circles have las a common external tangent? select all that apply. a and b a and c b and c

What is the surface area of the sphere?