E=number of eight cent stamps
t=number of ten cent stamps bought
w=number of 2 cent stamps bought
number of eight=number of ten
e=t
as many 2 cent as the other 2 combined
e+t=w or
2e=w=2t
total she bouthgt 4.40
4.40=440 cents
8e+10t+2w=440
solve for t or e, I solve for t
8t+10t+2(2t)=440
18t+4t=440
22t=440
divide 22
t=20
t=e
20=e
w=2e
w=2(20)
w=40
answer is
20 eight cent
20 ten cent
40 two cent
7/5 x 5/4
= 1 3/4
One and three fourths
(y^2)^5 × y^8
Use the rule:

To get:
y^10, then, use the rule:

To eventually get:
y^(10+8) = y^18 or: y18 seeing as you wrote it like that.
Split up the integration interval into 6 subintervals:
![\left[0,\dfrac\pi4\right],\left[\dfrac\pi4,\dfrac\pi2\right],\ldots,\left[\dfrac{5\pi}4,\dfrac{3\pi}2\right]](https://tex.z-dn.net/?f=%5Cleft%5B0%2C%5Cdfrac%5Cpi4%5Cright%5D%2C%5Cleft%5B%5Cdfrac%5Cpi4%2C%5Cdfrac%5Cpi2%5Cright%5D%2C%5Cldots%2C%5Cleft%5B%5Cdfrac%7B5%5Cpi%7D4%2C%5Cdfrac%7B3%5Cpi%7D2%5Cright%5D)
where the right endpoints are given by

for
. Then we approximate the integral

by the Riemann sum,


Compare to the actual value of the integral, which is exactly 4.