MHB What Was John's Salary After Giving His Mother 55%?

[Marcelo Arevalo]

At first, John wanted to give 30% of his salary to his mother. Finally, he decided to give her 55% of his salary but he would have $1,200 less for himself. How much was his salary?

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Let x be John's Salary
x (55%) = -$1200
x= 2181.1818?

 

[mathmari]

At the beginning when we wanted to give 30% of his salary to his mother, he woud have for himself 70% of the salary.
Now, giving his mother 55% of the salary, he has for himself 45% of the salary.

Substracting the amount that he has for himself now from the amount that he would have for himself at the beginning gives -1200$.

From that you can calculate the salary.

 

[Marcelo Arevalo]

I am confused with this problem. i am having a hard time figuring out the right equation.

 

[mathmari]

Let $x$ be John's salary.

At the beginning, John would have $70\%$ of $x $ for himself, so he would have $\frac{70}{100}x\$ $.
Now, he has $45 \%$ of $x $ for himself, so he has $\frac{45}{100}x\$ $.

We know that John has now $1200\$$ less than he would have at the beginning.

So, $$\frac{45}{100}x-\frac{70}{100}x=-1200$$

Solving this equation, you get the value of the salary $x$.

 

[Marcelo Arevalo]

now I get it.
John salary is :
x = 1200/0.25 = 4,800

thank you very much.

 

[Greg]

Assuming that John would have $\$1200$ less of $70\%$ of his salary if he gave his mother $55\%$,

$$\dfrac{70}{100}x-1200=\dfrac{45}{100}x$$.

 

[mathmari]

now I get it.
John salary is :
x = 1200/0.25 = 4,800

Yes. (Yes)

thank you very much.

You're welcome! (Smile)