Determine all values of c so that the lines cy=4x=9 and cy-5x=10 are perpendicular.
( do I try to get each letter its own answer for example c=--, y=--, x=--? how would I do that if I do?)

Question

Determine all values of c so that the lines cy=4x=9 and cy-5x=10 are perpendicular. 
( do I try to get each letter its own answer for example c=--, y=--, x=--? how would I do that if I do?)

aum · Answer

Are you sure the first equation is: cy=4x=9  ?

anonymous · Answer

sorry typo cy+4x=9

aum · Answer

Find the slope of the line cy + 4x = 9.
Put it in the slope-intercept form: y = mx + b.

aum · Answer

cy + 4x = 9.
subtract 4x:
cy = -4x + 9
divide by c:
y = (-4/c)x + 9/c
Slope of this line is -4/c

Find the slope of the line cy-5x=10  (use similar method as shown above).

If the lines are perpendicular the product of their slopes = -1.
Equate the product of the two slopes found above, equate it to -1 and solve for c.