Answer:
11.20
Step-by-step explanation:
Multiply both equations by 100:
19.99=1999
8.79=879
1999-879=1120
Divide by 100:
1120/100=11.20 saved ................
I remember CUP -- concave up positive. Here we have a leading coefficient that's negative, so the cup is upside down, the parabola opens down, an arch not a bowl.
Volume of the tank = length x width x height
Volume = 15.4 x 10 x 3 = 450 in³
Volume of one gallon = 231 in³
Then we need 450/231 gallons to fill the tank, that is 450/231 = 1.95 gallons