Question

7.5x+20y=900 models how many hours (x) and how many lawns mowed (y) Jon has to work in order to save $900. Give 3 combinations of hours worked and lawns mowed that result in $900.

Answer 1

ANSWER

$(1,\:\:44.625)$

$(2,\:\:44.25)$

$(3,\:\:43.875)$

EXPLANATION

We chose a value for $x$ and substitute in to the equation and solve for $y$.

If Jon works for $x=1$ hour,

Then the equation becomes,

$7.5(1)+20y=900$

We make $y$ the subject

$7.5+20y=900$

$20y=900-7.5$

$20y=892.5$

$y=\frac{892.5}{20}$

$y=44.625$

If Jon works for $x=2$ hours,

Then the equation becomes,

$7.5(2)+20y=900$

We make $y$ the subject

$15+20y=900$

$20y=900-15$

$20y=885$

$y=\frac{885}{20}$

$y=44.25$

If Jon works for $x=3$ hours,

Then the equation becomes,

$7.5(3)+20y=900$

We make $y$ the subject

$22.5+20y=900$

$20y=900-22.5$

$20y=877.5$

$y=\frac{877.5}{20}$

$y=43.875$

Therefore three combinations of hours worked and lawns mowed are

$(1,44.625)$

$(2,44.25)$

$(3,43.875)$