So you know that the area is greater than or equal to 60. Since 1/2 b x h is area, .5 x 12 x height (c) is greater than or equal to 60. Then solve, so .5 x 12 is 6, so 6c is greater than or equal to 60. then divide both sides by 6 and you end up with c is greater than or equal to 10
