sara spent 20.00 of her money on a gift for her mom, than half of her remaining money on a gift for her dad. sara last gift , for her brother, cost her 15.00. she left with 10.00. how much money did she start with?

Let X be what she started out with.

X-20 -(1/2)(X-20)-15 = 10
(1/2)(X-20) = 25
X-20= 50
X = 70