Question

How can I write this as an algebraic expression, " Julia spent $10 on school supplies. This was two thirds of the total amount of money she earned for the week".

Answer 1

x = total amount earned for the week

(2/3)x = 10 <== thats your algebraic expression

(2/3)x = 10 -- divide both sides by 2/3
x = 10/(2/3)
x = 10 * 3/2
x = 30/2
x = 15

check..
(2/3)x = 10
2/3(15) = 10
30/3 = 10
10 = 10 (correct)

Just so you know, she earned $15 for the week and 2/3 of it ($10) was spent on school supplies.