S8.4.2.48 find int given 2 areas

[karush]

screenshot to avoid typosok I assume f(x) is the eq of a sloped line.. well at the simplest option
at $2\ge x \ge 8$ so $y=\dfrac{7.3}{6}$ but I don't know how to get the slope so $\displaystyle\int_2^4 f(x) = 5.9$

 

[skeeter]

property of definite integrals ...

$\displaystyle \int_a^b f(x) \, dx + \int_b^c f(x) \, dx = \int_a^c f(x) \, dx$

 

[karush]

so $\displaystyle\int_4^8f(x) =7.3-5.9=1.4$