Which similarity postulate or theorem is it?

Mat bought a phone for $100. he has to pay $30 per mouth. if he has paid $640 in total, how many mouth has he had the phone?

Solve each quadratic equation by factoring and using the zero product property. x^2 - 8x + 30 = 3x

Apool measures 100 meters by 100 meters a toddler inside the pool and trows a ball 60 centimeters from one edge of the pool. how far is the ball from the opposite edge of the pool