Sarah W. answered • 02/03/16
Tutor
New to Wyzant
I Can Help You With Math!
You have a number written like AB where A is the digit in the 10s place and B is the digit in the ones place (the A and the B aren't multiplied here, they're just next to each other like the 4 and the 3 are when you write a number like 43).
The "unit's digit" is the same thing as the digit in the one's place. They say that it is 5 more than the tens digit.
B = A + 5.
They also say that AB is three times as great as the sum of its digits. AB isn't how we want to look at this number while doing this, it will be clearer what we're doing if we rewrite it as 10A + B (this comes from the fact that a number like 43 is the same thing as 4⋅10 + 3). Then
10A + B = 3(A + B)
This gives you a system of equations to solve. Reply if there are any problems with this.
Sarah W.
Did you try to work it out?
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02/04/16
Marvin B.
Yes but got a decimal
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02/05/16
Sarah W.
Alright, so let's look at it:
You have
B = A + 5
10A + B = 3(A + B)
for your equations.
Let's replace the Bs in the bottom equation with A + 5s, because we know that's the same thing from the top equation.
10A + A + 5 = 3(A + A + 5)
11A + 5 = 3(2A + 5) careful when you distribute the 3 here
11A + 5 = 6A + 15
5A = 10
A = 2
Then we know that B is 5 more than that, so B = 7.
Your number is 27.
We double check this and see that the 7 is five more than the 2. 27 is three times what we get when we add the digits (2 + 7 = 9).
Have a good weekend!
Report
02/05/16
Marvin B.
02/04/16