Question 196171
Let {{{a}}}= the average mpg for the 1st car
Let {{{b}}}= the average mpg for the 2nd car
given:
(1) {{{a + b = 45}}} mi/gal
(2) {{{40a + 20b = 1400}}} mi
Multiply both sides of (1) by 20
and subtract (1) from (2)
{{{40a + 20b = 1400}}}
{{{-20a -20b = -900}}}
{{{20a = 500}}}
{{{a = 25}}} mi/gal
and
(1) {{{a + b = 45}}}
{{{25 + b = 45}}}
{{{b = 45 - 25}}}
{{{b = 20}}} mi/gal
The 1st car got 25 mpg and the 2nd car got 20 mpg