Answer:
$0.90
Step-by-step explanation:
A 10-minute call exceeds the 3-minute initial period by 7 minutes. The initial period charge is 37¢. The additional minute charge is 7·9¢ = 63¢. Then the regular charge for that call is ...
37¢ +63¢ = 100¢ = $1.00
The 10% discount reduces the charge by ...
10% × $1.00 = $0.10
so the final cost of the 10-minute call is ...
$1.00 -0.10 = $0.90 . . . . . cost of the call
Let n be the amount of time it takes william to cut the lawn. Then Shelly takes
n-2 hours. So:
1/n+1/n-2=1/3
3(n-2)+3n=n²-2n
6n-6=n²-2n
n²-8n+6=0
Using the quadratic formula, we get a positive value of 7.1623 hrs as the amount of time william takes working alone, and 5.1623 as the amount of time Shelly takes working alone
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