Well I THINK triangle ABC is just a stretched out version of triangle DEF.
To find the area of a triangle, you multiply base and height, and divide by 2.
Area of DEF is 6, so that means that (4 * x)/2 = 6.
6*2 = 12....
4 * x = 12........
4 * 3 = 12.
x = 3.
Comparing DEF to ABC: ABC's base is 3 times as long as DEF's. So that means the height must be three times as long.
3*3 = 9.
(12 * 9)/2 =54
From the question we can deduce the formula to be 16 + 3n = 76
3n - 76 - 16
3n = 60
n = 20
20 is the answer.
60% - 3/5
Hope this help, don't really know what your expecting the answer to be