Question

Jim weighs 30 pounds less than Tom, and together they weigh 210 pounds. Let `n` Tom's weight in pounds. What would be the equation that expresses the total of Jim's and Tom's weights?

Answer 1

Jim and Tom's total weight is expressed by

`n+(n-30)=210`

and solving this equation tells us that Tom weighs 120 pounds, and Jim weighs 90 pounds.

Explanation:

If `n` is Tom's weight, then Jim's weight is

`n-30`

So an equation for their total weight would be

`n+(n-30)=210`

We could then continue to solve for `n` to find Tom's weight

`rArr2n-30=210`

`rArr2n-cancel30` `color(red)(+cancel30)=210` `color(red)(+30)`

`rArr2n=240`

`rArr(cancel2n)/color(red)cancel2=240/color(red)2`

`rArrn=120`

Tom weighs 120 pounds.

Jim's weight is then

`n-30`

`rArrcolor(red)120-30`

`rArr90`

Jim weighs 90 pounds.