CSS: Image and Text Margins

I’m trying to separate the margins of my image and text of a post.

.post .entry-content, .post .entry-summary {
	padding: 0 20px 20px;
}

.post p {
	margin-bottom: 20px;
}

.entry-content img {
	max-width: 100%;
	height: auto;
	margin: 0;
}

I can’t figure how to put NO margin on the image but have 20px left/right/bottom/top on the text. Can someone help me figure this out? I may need to alter the php as well?

Thank you!!!

-nD