Cuál es el aumento de 645 teléfonos por 35% por año hasta el 2010

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

On saturday a souvenir shop had 125 customers. sixty four percent of the costumers paid with a credit card. how many costumers paid with cash?

What is the axis of symmetry of the function f(x)=-(x+ 9)(x-21)