A man spends one fifth of the money in his wallet . He then spends one fifth of what remains in the wallet. He spends $36.00 in all. How much money did he have to begin with?
A man spends one fifth of the money in his wallet . He then spends one fifth of what remains in the wallet. He spends $36.00 in all. How much money did he have to begin with?
x = Money to begin
\(\begin{array}{c|l|r} \hline & \text{wallet} &\text{giving dollar} \\ \hline & x & 0 \\ &(x)-\frac15\cdot x & \frac15\cdot x \\ &(x-\frac15\cdot x) -\frac15(x-\frac15\cdot x) & \frac15(x-\frac15\cdot x)\\ \hline \text{sum} && $36\\ \hline \end{array}\)
\(\begin{array}{rcl} \frac15\cdot x + \frac15(x-\frac15\cdot x) &=& $36 \quad & | \qquad \cdot 5 \\ x + x-\frac15\cdot x &=& $180 \\ 2x-\frac15\cdot x &=& $180 \quad & | \qquad \cdot 5 \\ 10x-x &=& $900 \\ 9x &=& $900 \quad & | \qquad :9 \\ \mathbf{ x } & \mathbf{=} & \mathbf{$100} \\ \end{array}\)
To begin he has $100.
\(\begin{array}{c|l|r} \hline & \text{wallet} &\text{giving dollar} \\ \hline & \mathbf{$100} & 0 \\ & $100-$20=$80 & \frac{$100}{5}=$20 \\ & $80-$16=$64 & \frac{$80}{5} =$16\\ \hline \text{sum} && $36\\ \hline \end{array}\)
Let x be the amount he started with
So....he first spends 1/5 of this = (1/5)x
So....what's left = (4/5)x
And he spends (1/5) of this = (1/5)(4/5)x = (4/25)x
So he spends (1/5)x + (4/25)x and this = $36.......so we have
(1/5)x + (4/25)x = 36
(5/25)x + (4/25)x = 36
(9/25)x = 36 multiply both sides by 25/9
x =36 (25/9)
x = (36/9) * 25
x = 4 * 25 = $100 and this is what he started with
Proof......he spends 1/5 of $100 = $ 20
Then....he spends 1/5 of what's left = (1/5)($80) = $16
And $20 + $16 = $36
A man spends one fifth of the money in his wallet . He then spends one fifth of what remains in the wallet. He spends $36.00 in all. How much money did he have to begin with?
x = Money to begin
\(\begin{array}{c|l|r} \hline & \text{wallet} &\text{giving dollar} \\ \hline & x & 0 \\ &(x)-\frac15\cdot x & \frac15\cdot x \\ &(x-\frac15\cdot x) -\frac15(x-\frac15\cdot x) & \frac15(x-\frac15\cdot x)\\ \hline \text{sum} && $36\\ \hline \end{array}\)
\(\begin{array}{rcl} \frac15\cdot x + \frac15(x-\frac15\cdot x) &=& $36 \quad & | \qquad \cdot 5 \\ x + x-\frac15\cdot x &=& $180 \\ 2x-\frac15\cdot x &=& $180 \quad & | \qquad \cdot 5 \\ 10x-x &=& $900 \\ 9x &=& $900 \quad & | \qquad :9 \\ \mathbf{ x } & \mathbf{=} & \mathbf{$100} \\ \end{array}\)
To begin he has $100.
\(\begin{array}{c|l|r} \hline & \text{wallet} &\text{giving dollar} \\ \hline & \mathbf{$100} & 0 \\ & $100-$20=$80 & \frac{$100}{5}=$20 \\ & $80-$16=$64 & \frac{$80}{5} =$16\\ \hline \text{sum} && $36\\ \hline \end{array}\)