Answer: [tex]\geq[/tex] 9 lawns, assuming Fiona spends 1 hour per lawn.
Step-by-step explanation:
Let Y = the amount earned from mowing a lawn. Let z be the number of hours worked on that lawn.
Y = $10 + $5(z)
We need to know the number of hours, z, for any particular lawn to be able to make this a valid equation. Not having that, we really can't set up a valid equation.
But let's assume z=1 for each and every lawn and see what we'd have.
Y = $10 + $5
Y = $15/lawn.
Fiona needs at least $135 for her Broadway ticket.
Let L be the number of lawns mowed. We need:
L*($15/lawn) [tex]\geq[/tex] $135
L [tex]\geq[/tex] 9 lawns