Excel Formula

Hello,
i have a gradeing scale on one sheet, and on the other, i have my grades as percentages, and the amount of points the assignment was worth. I need a way connect the two sheets so that if in cell E1 i have 100%, than there will be a formula in the cell to show that it is an A+. Please help and thank you in advance
100 A+
99 A+
98 A+
97 A
96 A
95 A
94 A-
93 A-
92 B+
91 B+
90 B+
89 B
88 B
87 B
86 B-
85 B-
84 C+
83 C+
82 C+
81 C
80 C
79 C
78 C-
77 C-
76 D+
75 D+
74 D
73 D
72 D
71 D-
70 D-
69 F