Convert 7yards 2foot in inches

Two sides of a triangle mesure 20cm and 30cm. what is the measure of the third side

Ineed to know the answer to this algebra question.

Aprojectile is thrown upward so that its distance above the ground after t seconds is given by the function h(t) = -16t2 + 704t. after how many seconds does the projectile take to reach its maximum height?