How do you Calculate volume of attached solid

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 you have 12 feet of string and you cut it into equal length of 5 inches each how much string will be left

Solve for x in the equation x2 - 12x + 36 = 90. x= 6+3x/10 x=6+2/7 x= 12+3/22 x = 12+3/10