Question 236779
To solve by substitution:
1. Leave first equation alone for now.
2. Solve for y on the second equation.
3. Plug in this value into the first eqn to find x
4. Once you know the x value, plug it again in the forst equation to find y.
.
Problem:
{{{x+y=7}}}
{{{x+2y=11}}}
so...
{{{2y=11-x}}}
{{{y=(11-x)/2}}}
now plug into first eqn...
{{{x+((11-x)/2)=7}}}
Multiply entire eqn by 2 to eliminate the fraction.
{{{2*x+2*((11-x)/2)=2*7}}}
{{{2x+(11-x)=14}}}
Now combine like terms to solve for x
{{{2x-x=14-11}}}
{{{x=3}}}
Now plug this value in the first equation to solve for y.
{{{x+y=7}}}
{{{3+y=7}}}
{{{y=7-3}}}
{{{y=4}}}