Question

Mingfa says, "My sister and I have $130 altogether. If my mother gives me another
$10, I'll have 3 times as much money as my sister."
How much money does Mingfa actually have?​

Answer 1

Given:

Total amount of Mingfa and her sister = $130

If Mingfa amount increased by $10, then the new amount is equal to three times of as much money as her sister.

To find:

How much money does Mingfa actually have?​

Solution:

Let, Mingfa have $x and her sister has $y initially. Then,

$x+y=130$                ...(i)

If Mingfa amount increased by $10, then the new amount is equal to three times of as much money as her sister.

$x+10=3y$              ...(ii)

Substitute the value of x from (ii) in (i).

$(3y-10)+y=130$

$4y=130+10$

$4y=140$

Divide both sides by 4.

$y=35$

Putting $y=35$ in (i), we get

$x+35=130$

$x=130-35$

$x=95$

Therefore, Mingfa have $95.