Question 132066
(1) {{{1.25x + 1.1y = 1520}}}
(2) {{{1.1x + 1.25y = 1535}}}
Notice that in (2), {{{1535 = 1520 + 15}}}, so rewriting,
{{{1.1x + 1.25y = 1520 + 15}}}
(3) {{{1.1x + 1.25y - 15 = 1520}}}
Set the left side of (1) equal to the left side of (3)
{{{1.25x + 1.1y = 1.1x + 1.25y + 15}}}
{{{.15x - .15y = 15}}}
divide both sides by {{{.15}}}
{{{x + y = 100}}}
{{{y = 100 - x}}}
Substitute this in either equation
{{{1.25x + 1.1(100-x) = 1520}}}
{{{1.25x + 110 - 1.1x = 1520}}}
{{{.15x = 1410}}}
{{{x = 9400}}} answer
{{{y = 100 - x}}}
{{{y = -9300}}} answer
check answers:
(1) {{{1.25x + 1.1y = 1520}}}
{{{1.25*9400 + 1.1*(-9300) = 1520}}}
{{{11750 - 10230 = 1520}}}
{{{1520 = 1520}}}
OK