The height, in meters ,of a projectile can be modeled by the function f(t)=-4.9t^2+19.6t+50, where t is the number of seconds since the object was launched. how long does it take to reach max height after it launches?​

The first week samantha learned to read braille, she could read 10 words per minute. in the second week she increased her speed by 20%. in the third week she increased her speed again by another 25%. how many words could she read per minute by the third week? hurry and tell me!