Question 1123763
Same way or same idea as your other two.


Using your direct-variation language, you can start with
{{{y=kx}}}
y, amount of income
x, number of lawns
k, variation constant



{{{k=y/x}}}

{{{143.5/7}}}

{{{k=20.5}}}

Your model becomes  {{{highlight_green(y=20.5x)}}}.



If 10 lawns, just substitute into your formula model and evaluate y.