Calculate the left and right Riemann sums for ${\int }_1^4(2-x)dx$ with $n=6$ subintervals.

Left Riemann Sum: $\frac{9}{4}$

Right Riemann Sum: $\frac{3}{4}$

Left Riemann Sum: $-\frac{9}{4}$

Right Riemann Sum: $-\frac{3}{4}$

Left Riemann Sum: $-\frac{3}{4}$

Right Riemann Sum: $-\frac{9}{4}$

Left Riemann Sum: $\frac{3}{4}$

Right Riemann Sum: $\frac{9}{4}$