How do I tone my abs?

I'm not really fat but after 4 kids my stomach isn't as tight. I weigh about 115-120 pounds. So my question is can I tone up my abs with daily 30 mins of exercise but still see results without changing my diet?
I know the results would come faster but I'm not big on calorie counting and stuff. And also its not like I pig out on junk food but I do love my pasta and hamburgers. And dessert
Would portion control and exercise get me what I want to accomplish?
How do I tone my abs?
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