Question 306408
w + z = 380
w + x = 600
x - y = 170
y - z = 50


id start working backwards
{{{y-z=50}}}solve for y
{{{highlight(y=z+50)}}}
{{{x-y=170}}} solve for x
{{{x=170+y}}} fill in y with what it equals
{{{x=170+(z+50)}}}
{{{highlight(x=220+z)}}}
{{{w+x=600}}}solve for w
{{{w=600-x}}} substitute for x
{{{w=600-(220+z)}}}
{{{highlight(w=380+z)}}}
{{{w+z=380}}} solve for z
{{{z=380-w}}} substitute for w
{{{z=380-(380+z)}}}
{{{0=0}}}
so z can be any number
so if z=1 then x=221 y=51 w=381
if z=2 then x=222 y=52 w=382
if z=3 then x=223 y=53 w=383
and so on
{z=|(-∞,+∞)}
all real numbers