The length of the shorter base of a trapezoid, s, is 3 less than 2 times the longer base of the trapezoid, 1. Which equation can be used to determine the length of the shorter base of the trapezoid?
A S = 3-21
B S = 21-3
T +3
С S =
2
D S = 21 +3

Sanderson is having trouble with his assignment. his shown work is as follows: − 3 7 7 3 = − 3 7 × 7 3 = − 21 21 = −1 however, his answer does not match the answer that his teacher gives him. complete the description of sanderson's mistake. find the correct answer.