Question

This week, Luis made 80% of what he made last week. If he made $72 this week, how much did he make last week?

Answer 1

Answer :

He made $90 last week.

Assumption :

Let, Luis made $X last week.

He made $72 this week which is 80% of $X that he made last week

⇒ X * 80% = 72

⇒ X * 80/100 = 72

⇒ X = (72 * 100)/80

⇒ X = 90

Therefore, he made $90 last week.

To remember :

While solving this type of problems, be careful to understand which one of last time and current time is not given; just assume that one and input other conditions, the problem will be solved.

Answer 2

$\textbf{\underline{\underline{Answer :-}}}$

Luis made $90 in the last week.

$\textbf{\underline{\underline{Explanation :-}}}$

$\textsf{\underline{\underline{Given :}}}$

This week,Luis made = 80% of last week.

Money he made this week = $72

$\textsf{\underline{\underline{To find :}}}$

Money he made last week.

$\textsf{\underline{\underline{Solution :}}}$

Consider the amount he made in last week as x

So, 80% of x will be $72

★ Equation : $\boxed{\sf{80\%\:of\:x = 72}}$

$\sf{\implies} \: 80\% \: \times x = 72$

$\sf{\implies} \: \dfrac{80}{100} \times x = 72$

$\sf{\implies} \:80x = 72 \times 100$

$\sf{\implies} \: 80x = 7200$

$\sf{\implies} \: x = \dfrac{7200}{80}$

$\sf{\implies}\red{ \: x = 90}$

$\therefore$ Luis made $90 in the last week.

$\textbf{\underline{\underline{Verification :-}}}$

We can verify it by solving for 80% of 90

$\sf{\implies} \: 80\% \: of \: 90$

$\sf{\implies} \: \dfrac{80}{100} \times 90$

$\sf{\implies} \: \dfrac{72 \: {\cancel{00}}}{1 \: {\cancel{00}}}$

$\sf{\implies}\red{ \: 72}$

$\therefore$ Luis made $90 in the last week.