# Thread: Simple question but need help

1. ## Simple question but need help

They give answer in attachment but I dont get " back solving" how do you do that??

2. ## Re: Simple question but need help

The first equation is

$13 b + 4t = 487$

They've solved for $b=23$

Then back solving is taking the value of $b$ and plugging it back into one of the original equations, i.e.

$13(23) + 4t = 487$

and solving for the remaining variable $t$

$299 + 4t = 487$

$4t = 188$

$t = 47$

3. ## Re: Simple question but need help

Thank you so much, but I'm also confused on how they solved for b.

B = 487 - 4t / 13 ....?

4. ## Re: Simple question but need help

$13b + 4t = 487$

$6b + 2t = 232$

subtract twice the 2nd equation from the first

$(13-12)b + (4-4)t = 487-(2)(232)$

$b = 23$

5. ## Re: Simple question but need help

OMG Thank you so much. I would have never know to subtract 2 time

Thank you!!