Posted by Miranda on .
Cecil has a mysterious money machine that will double any amount of money placed in it and add $5.00 to the doubled amount. Yesterday, he placed a certian amount of money in the box, got a new amount, then placed the new amount back in the box. Then he had $51.00. How much money did he first place in the mysterious money machine?

math 
Guido,
Machine will:
*double any amount placed inside
*add $5 to the amount that is doubled
*a total of $51 was the end result
Let x = how much money he first placed in the box.
Let 2x = the double amount
2x + 5 = 51
2x = 51  5
2x = 46
x = 46/2
x = $23
Done!