The area of a triangle is given by b/2 * h

So

60 = 15/2 * h

60 = 15h/2

divide both sides by 15

4 = h/2

multiply both sides by 2 and transpose sides

h = 8

check 7.5 * 8 = 60

height is 8 yards

So

60 = 15/2 * h

60 = 15h/2

divide both sides by 15

4 = h/2

multiply both sides by 2 and transpose sides

h = 8

check 7.5 * 8 = 60

height is 8 yards