Please help me please!

List x1, x2, x3, x4 where xi is the left endpoint of the four equal intervals used to estimate the area under the curve of f(x) between x = 4 and x = 6. a 4, 4.5, 5, 5.5 b 4.5, 5, 5.5, 6 c 4.25, 4.75, 5.25, 5.75 d 4, 4.2, 5.4, 6

If f(x) = 6x – 4, what is f(x) when x = 8? a2 b16 c44 d52

Agallon of apple juice cost $7 a pack of eight 4.23oz box of apple juice $2.39 which is a better deal