CPM Homework Help : CALC Problem 2-109

The sigma notation below represents Riemann sums that find $A(f, a ≤ x ≤ b)$ for $n$ rectangles of equal width. Determine $a$ , $b$ , and $n$ .

$\displaystyle\sum _ { i = 0 } ^ { 17 } \frac { 1 } { 3 } f ( - 6 + \frac { 1 } { 3 } i )$

$\displaystyle\sum _ { i = 0 } ^ { 9 } \frac { 1 } { 10 } f ( 4 + \frac { 1 } { 10 } i )$

Hint:

General form of left-endpoint Riemann Sum:
$n$ represents number of rectangles
$a$ represents starting value on the $x$ -axis
$\Delta x$ represents width of each rectangle: $\frac{b-a}{n}$