Split up the interval [0, 3] into 3 equally spaced subintervals of length
. So we have the partition
[0, 1] U [1, 2] U [2, 3]
The left endpoint of the
-th subinterval is

where
.
Then the area is given by the definite integral and approximated by the left-hand Riemann sum

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5/8 9/x
Cross multiply
9x8=72
5×x=5x
Rewrite the equation
72 = 5x
Divide by 5
72÷5=14.4
So, x=14.4
The ratio from 80 to 5 would be 16. so divide 144 by 16 and you get 9. Answer:9