This is the distributive property. You take what is outside of the parenthesis and DISTRIBUTE it inside the parenthesis.
Let the number of gallons consumed be the first car be x, and that of the second car, y. Then:
x + y = 50 . . . . . . . (1)
20x + 15y = 850. . . (2)
(1) x 20 => 20x + 20y = 1000 . . . (3)
(2) - (3) => -5y = -150 => y = -150/-5 = 30
From (1), x + 30 = 50 => x = 50 - 30 = 20
Therefore, first car consumed 20 gallons and the second consumed 30 gallons.
Collect like terms
6.5x-4.5x = 6+10
2x = 6+10
Divide both sides
2x = 16
X= 8
Answer:
the answer is 1000 metres
