Use the figures to calculate the left and right Riemann sums for $f$ on the given interval and the given value of $n$.
\[
f(x)=x+5 \text { on }[1,6] ; n=5
\]
The left Riemann sum is $\square$. (Simplify your answer.)

Step 1 ：We are given the function \(f(x) = x + 5\), the interval \([1, 6]\), and \(n = 5\).

Step 2 ：The left Riemann sum is a method of approximating the area under a curve. It is calculated by dividing the area under the curve into rectangles and summing the areas of these rectangles. The left Riemann sum uses the left endpoints of each subinterval to calculate the height of each rectangle.

Step 3 ：The formula for the left Riemann sum is \(L_n = \sum_{i=1}^{n} f(x_{i-1}) \Delta x\), where \(n\) is the number of subintervals, \(f(x_{i-1})\) is the value of the function at the left endpoint of the \(i\)th subinterval, and \(\Delta x\) is the width of each subinterval.

Step 4 ：In this case, the width of each subinterval is \(\Delta x = \frac{6 - 1}{5} = 1\).

Step 5 ：The left endpoints of the subintervals are \(x_0 = 1, x_1 = 2, x_2 = 3, x_3 = 4, x_4 = 5\). We can substitute these values into the function to get the heights of the rectangles.

Step 6 ：Substituting these values into the function, we get \(f(1) = 6, f(2) = 7, f(3) = 8, f(4) = 9, f(5) = 10\).

Step 7 ：Multiplying these values by the width of the subintervals and summing, we get the left Riemann sum: \(6*1 + 7*1 + 8*1 + 9*1 + 10*1 = 40\).

Step 8 ：Final Answer: The left Riemann sum is \(\boxed{40}\).