Mr. jones replace 40% of the lights on a christmas tree. if he replaced 30 lights, how many lights are on the tree total?

Since 30 lights are 40% of them:

30*2= 60

Since 2*40= 80

We still need the 20 percent.

Half of 40= 20.

30/2= 15

So, 15+60= 75

75 is the number of lights on the tree.

I hope this helps!
~cupcake

This is how I looked at it. If there are 30 lights in 40% then there are 15 lights per 20%.
15 x 5= 75