How to do it. how to find the area. how to find the perimeter

After the seventh month of a 12-month loan: the numerator is: {(n + 11) + (n + 10) + (n + 9) + (n + 8) + (n + 7) + (n + 6) + (n + 5)} = , and the denominator is: {(n) + (n + 1) + + (n + 11)} = . therefore, the fraction is numerator/denominator (to the nearest tenth) = %

How many triangles can be drawn with side lengths 4 centimeters, 4.5 centimeters, and 9 centimeters? explain

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?