Kim had 160 cards in a box. she gave 4/10 of the cards to maddy. how many cards did kim have left in the box

this may not be at all, but i use the same website you're using for school, and if i'm stuck doing one of these i try to look for it on the section.

take the logarithm of both sides (the base of the log doesn't matter):

apply the exponent property - this says that :

distribute the log terms on both sides:

group like terms together:

divide through both sides by the coefficient on :

you can do some additional rewriting here using the properties of the logarithm to simplify things if you like: