B. (9,126)
<span>y + 18 = 16x
=>y=16x-18
0.5x + 0.25y = 36 (multiply both sides by 4)
=>2x+y = 144
Substitute y=16x-8
=>2x+16x-8=144
=>18x=152
=>x=152/18=9
y=16x-18
=>y=16(9)-18
=>y=144-18=126
Answer: x=9 and y=126</span>
Ok so we know he used over 700 because he was charged more than 40. Then we take the $8.10 and divide 0.45 into it. This then gives you 18 more minutes. Then add 18 to 700 and you get 718 min.
It would be 384.58, or 384.57909
