You can
put this solution on YOUR website!Let x=tens digit, y=units digit
Since "The tens digit is 6 more than the units digit" we get
Since the number is between 300 and 400, we know that the number must be of the form

and since the number is 40 times the sum of the digits, we then have the equation

Distribute

Now plug in

Distribute again

Combine like terms

Subtract 11y from both sides

Subtract 360 from both sides

Combine like terms

Divide both sides by 91
So the units digit is 0
This means the tens digit is:
So we have:
tens digit: 6 , ones digit: 0
-----------------------------------------
Answer:
So our number is 360
Check:
Notice if we add the digits of 360, we get
3+6+0=9
Now multiply the sum by 40
9*40=360
which is our number. So our answer is verified