Question

Alex spent 1/3 of his pocket money on a toy airplane and 2/3 of the remainder on a toy robot. He had $20 left. How much did he spend altogether?

Answer 1

He spent $70 in total! He spent ⅓ of his money on a toy plane remainder ³/³ -
⅓ = ⅔. Spent on toy robot = 2/3 * 2/3 = 4/9
Total spent = 1/3 + 4/9 = 3/9 + 4/9 = 7/9
Left = 9/9 - 7/9 = 2/9
Then the final step,
2/9 to $20
1/9 to 20/2 = $10
7/9 to 10*9 = $70

Answer 2

Answer with explanation:

Let Pocket money Alex =$ x

Amount of money spent on toy Airplane
`=(x)/(3)`

Money left with Alex

`x-(x)/(3)=(2x)/(3)`

Amount of money spent on toy Robot

`=(2x)/(3)*(2)/(3)\\\\=(4x)/(9)`

Amount left after these two expenses=$ 20

Writing the above statement in equation form

`\rightarrow (x)/(3)+(4x)/(9)+20=x\\\\(7x)/(9)+20=x\\\\x-(7x)/(9)=20\\\\(2x)/(9)=20\\\\x=(180)/(2)\\\\x=90`

So, Money spent by Alex =$90-$20

=$ 70