Question 205647
Yes, You have the right idea but you messed up in the beginning
1. First the perimiter equation
- {{{168=2L+2W}}}
2. then set up an equation that states L in terms of W (in other words ex. L=2W) here is where you made your error
- {{{L=3w+12}}}
3. Now you have a systmes of equations
- {{{168=2L+2W}}}
- {{{L=3w+12}}}
4. Substitute the 2nd equation into the 1st equation
- {{{168=2(3W+12)+2W}}}
5. Then solve for W
- {{{168 = 6W+24+2W}}}
- {{{168 = 8W+24}}}
- {{{168-24 = 8W+24-24}}}
- {{{144 = 8W}}}
- {{{144/8 = 8W/8}}}
- {{{18=W}}}
6. Now plug in the value for W into the 2nd equation
- {{{L=3(18)+12}}}
- {{{L=54+12}}}
- {{{L=66}}}
7. So the dimensions of the driveway are W = 18ft and L = 66ft
8. And finally plug them back in to check you numbers
- {{{168 = 2(18)+2(66)}}}
- {{{168 = 36+132}}}
- {{{168 = 168}}}