We can create an equation to represent this situation.
Let xx = the total amount of money that Mary had at first (before she bought anything.)
Mary started with color(blue)(x)x dollars. After she spent color(red)(2/5)25 of her color(blue)("money")money on a handbag and color(violet)($20)$20 on a belt, she had color(green)($25)$25 left.
color(green)(25) = color(blue)(x) - color(red)(2/5) color(blue)(x) - color(violet)(20)25=x−25x−20
1. Combine like terms.
25 = 3/5x - 2025=35x−20
2. Add 20 to both sides.
25 + 20 = 3/5x cancel( -20) cancel(+20)
45 = 3/5x
3. Divide both sides by 3/5 (or multiply both sides by 5/3 - shown here) to find x.
(5/3)45 = 3/5x(5/3)
x = 75
She had $75 at first.
Hope this helps!
