Substitute 5,3,4 and 4 1/2 into from question 1 part A which of these values result in a valid equation

Can someone check if i did this correct. it’s number 4 if you’re wondering.

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

What number is 7 units left of -15?