Total raised: 264
She raised 30 plus 1.80x (x being the number of minutes).
Equation: 264=1.8x+30
To solve for x, you need to isolate x. First, subtract 30 from both sides.
234=1.8x
Now, divide both sides by 1.8.
130=x
Marni danced 130 minutes.
I hope this helps :)