I believe it is 3.333333333%
Get rid of parenthesis, this is addition it doesn't matter how you add it will give you the same answer
3/8+2/3+1/3
3/8+3/3
3/8+1
3/8+8/8
11/8→1 3/8→1.375
16 cm - 2.5 cm = 13.5 cm, which is 1/4 of the diameter of the large gear. Take 13.5 cm * 4, and you have the diameter of the large gear, which is 54 cm.
The equation of a line which has the slope m and passes through the point A(x1,y1) has the formula:
y-y1=m(x-x1)
in your case m= -5 ; A(x1;y1)=(1;-1)
y-(-1)= -5(x-1)
y+1= -5(x-1)
answer is c