Answer:
yes they form a proportion
200 because 15 - 5 is 10 and 15+5 is 20. so 15 squared is 225 and 5 squared is 25 and 225-25 is 200
For the matrix

the determinant using the method of expansion by minors, expanding on the third row is:

Answer:
First, we compute the determinants of the minors:

Therefore:
Answer:
t= 0.8 hr or 48 min.
Step-by-step explanation:
Speed of Enrique= 6 mph
Half and hour late it means that after 1/2 hr.
Speed of Enrique brother = 8 mph
Lets take Enrique cover x distance in time t hr .
So
x = 6 t ------------ 1
Then his brother will cover x/2 distance in time (t-1/2) hr.
So
x/2 = 8 (t-1/2) -----------------2
Now from equation 1 and 2
6 t = 16 (t-1/2)
6 t = 16 t - 8
So t= 0.8 hr or 48 min.
It means that his brother will take 0.8 hr to cover half of distance cover by Enrique .