What are three way that you can call a rhombus? ?

Which shows the correct solution of the equation 1/2a+2/3b=50, when b=30?

1. writing an equation for an exponential function by 2. a piece of paper that is 0.6 millimeter thick is folded. write an equation for the thickness t of the paper in millimeters as a function of the number n of folds. the equation is t(n)= 3. enter an equation for the function that includes the points. (-2, 2/5) and (-1,2)

Angles r and s are complementary. the measure of angle r is 31 degrees. which equation can be used to find angle s?