Tu puntuación promedio en cuatro exámenes es 64, que puntuación necesitas en el quinto examen para obtener un promedio de 70

1) ratio of number of seats to the number of minutes: 2 seats / 11 minutes

2) proportion relating the number of seats s to the number of minutes m:

s / m = 2 seats / 11 minutes

3) How long will it take to add 16 seats

16 seats / x = 2 seats / 11 minutes

=> x = 16 seats * 11 minutes / 2 seats = 88 minutes

4) How long will it take to add 19 seats:

19 seats / x = 2 seats / 11 minutes

=> x = 19 seats * 11 minutes / 2 seats = 104.5 minutes.