A variable needs to be eliminated to solve the system of equations below. Choose the correct first step.
-10x + y = 64
-10x + 5y = 40

Cody worked 42.5 hours per week in july. this is 12.25 hours more per week than he worked in june. how many hours did cody work per week in june?

The marriott family bought a new apartment three years ago for $65,000. the apartment is now worth $86,515. assuming a steady rate of growth, what was the yearly rate of appreciation? what is the percent of the yearly rate of appreciation?

The graph of y = ax^2 + bx + c is a parabola that opens up and has a vertex at (0, 5). what is the solution set of the related equation 0 = ax%2 + bx + c?