A set of speakers that originally sells for $225 is currently on sale for 20% off. How much does the set of speakers currently cost?

What is the range? can’t seem to find it out

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

Solve -.016x= -16. need solving this