I dont understand how to solve problem number 6 please help.

I dont understand how to solve problem number 6 please help. ATTACHMENT PREVIEW Download attachmentScreenshot (17).pngIn Exercises 5-14, find the approximate area under the curves of the
given equations by dividing the indicated intervals into n subintervals
and then add up the areas of the inscribed rectangles. There are two
values of n for each exercise and therefore two approximations for
each area. The height of each rectangle may be found by evaluating
the function for the proper value of x. See Example 1.
5. y = 3x, between x = 0 and x = 3, for
(a) n = 3(Ax = 1), (b) n = 10 (Ax = 0.3)
6. y = 2x + 1, between x = 0 and x = 2, for
(a) n = 4(Ar = 0.5), (b) n = 10 (Ax = 0.2)