8hrs = 480mins
6hrs = 360 mins
472/480 = 0.983...
0.983... x 360 = 354
D) 354
DE + EF = 4x+2
DE = x+7
EF = 7
Substitute these in
x + 7 + 7 = 4x + 2
x + 14 = 4x + 2
subtract x from both sides
14 = 3x + 2
subtract 2 from both sides
3x = 12
divide both sides by 3
x = 4
substitute this in to find the length of DE
DE = x + 7
(4) + 7 = 11
the answer is 11
The first one. For a triangle to be considered a right triangle a^2+b^2 has to equal c^2
