Part a : you could draw a line from each corner to the middle
This would give you 7 triangles in total
Part b : area of one triangle : 4.5*7.8 = 35.1 / 2 = 17.55in <-- area of 1 triangle
Part c : so if there are 7 triangles and the area of 1 triangle is 17.55, you would do:
7 * 17.55 = 122.85
10m ----> 3 sec
x meters ----> 50 sec
50(10) = 3x
500 = 3x
devide both in 3
x = 166.66 m
34= 12+(8)2+(3)2
youre basically just plugging in the numbers to the letter they correspond