Question 741320

let numbers be {{{x}}} and {{{y}}}

if the sum of two numbers is {{{28}}}, we have

{{{x+y=28}}}....eq.1

 and if their difference is {{{4}}}, we have


{{{x-y=4}}}....eq.2

solve the system by addition:

{{{x+y=28}}}....eq.1
{{{x-y=4}}}....eq.2
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{{{x+x+cross(y)-cross(y)=28+4}}}

{{{2x=32}}}

{{{x=32/2}}}

{{{highlight(x=16)}}}

now find {{{y}}}

{{{16+y=28}}}....eq.1

{{{y=28-16}}}

{{{highlight(y=12)}}}

check:

{{{x+y=28}}}....eq.1

{{{16+12=28}}}

{{{28=28}}}


{{{x-y=4}}}....eq.2

{{{16-12=4}}}

{{{4=4}}}