Question

What is the value of x x-2/5 =7 what is the value of x

Answer 1

The answer could be 37

Answer 2

Consider the puzzle:

"I have In mind a (secret) number. When I subtract 2/5 from this number I get 7. What is the number?"

To solve such puzzles we go backwards. We got 7 after we subtracted 2/5, so if we add 2/5 to 7, we get the secret number back.

Solving an equation is solving a puzzle about a secret number, which we call "x" instead of saying "something", all the time.

going backwards, means adding, if we subtracted, or dividing, if we multiplied.


So, to solve
`x- (2)/(5)=7`, we just need to add 2/5 back to x:


`x- (2)/(5)=7`


`x- (2)/(5)+(2)/(5)=7+(2)/(5)`


`x=7+(2)/(5)`

to add 7 and 2/5, multiply 7 by 5/5

7+2/5=7.(5/5)+2/5=35/5+2/5=37/5



Thus x= 37/5