For positive acute angles A
A and
B
,
B, it is known that
cos
⁡
A
=
4
5
cosA=
5
4
​
and
sin
⁡
B
=
15
17
.
sinB=
17
15
​
. Find the value of
cos
⁡
(
A
−
B
)
cos(A−B) in simplest form.

The customer price index(cpi), which measures the cost of a typical package of customer goods, was 208.8 in 2011 and 244.1 in 2016.let x=11 corresponding to the year 2011 an estimate to cpi into 2013 and 2014. assume that the data can be modeled by a straight line and the trend to continue idenfinitely. use data points to find such a line and then estimate the requested quantities