Answer
Smartphone costs ${{\$}} 325$
Tablet costs ${{\$}} 640$
Work Step by Step
Let
$x = $ cost of smartphone,
$y = $ cost of tablet.
Given: $\left\{\begin{array}{llll}
340x+250y=270,500 & ... preorders & & (1)\\
x+y=965 & \Rightarrow & y=965-x & (2)
\end{array}\right.$
Substitute y into (1)
$340x+250(965-x)=270,500$
$340x+241,250-250x==270,500$
$90x=29250$
$x=325$
Back-substitute into (2)
$y=965-325=640$
