Problem:
If 60a=3 and 60b=5, then 12[(1−a−b)/2(1−b)] is
Answer Choices:
A. 3​
B. 2
C. 5​
D. 3
E. 12​
Solution:
12=560​=60b60​=601−b. So
12[(1−a−b)2(1−b)]​=[601−b](1−a−b)/2(1−b)=60(1−a−b)/2=60a60b60​​=3⋅560​​=2.​