Answer:
I'm pretty sure the answer is 8.96
Step-by-step explanation:
1.28×7=8.96
He made $40 those 5 days.
8•5=40
Let's call the first unknown integer x and the second one y.
"Four times an unknown integer"
"Multiplied by three times the unknown integer plus a different unknown integer"
- 4x is multiplied by 3x+y, so 4x(3x+y)=12x²+4xy
"Equals 100."
And so the answer is C: 12x²+4xy-100=0