Answer is 12, they spilt 1/5 on the way to the lemonade stand 180 x 1/5 = 180/5 = 36 so they spilt 36 cups of lemonade on the way to the stand number of cups left 180- 36 = 144. They sold 75% of 144 cups of lemonade 75/100 x 144 (divide both 75 and 100 by 25) = 3/4 x 144 (divide 144 by 4) =3 x 36 = 108 so they sold 108 cups of lemonade number of cups left 144-108 = 36 they spilt 1/3 of 36 cups of lemonade on the way home. 36 x 1/3 = 36/3 = 12 therefore they brought back 12 cups of lemonade home.