Answer:
Billy is a fly enthusiast! He has a huge glass container filled with 506 flies! One day when Billy went to feed the flies, he accidentally left the screw opened for too long, and 8 flies escaped! How many flies are left in the tank?
Its a simultaneous equation:
lets make "x" the used games and "y" the new ones
4x + 2y = 84
6x + y = 78. (multiply this by 2 to cancel out y)
12x + 2y = 156
so now we subtract them:
12x - 4x = 156 - 84
x = 9
used games cost $9
new games cost 78 - 6(9) = $24
Janet has $120 but she already bought 3 NEW games so:
120 - 3(24) = $48 left
48/9 = how many used ones she can buy = 5. something
she can buy 5 used
3.
30 divided by 10 equals 3
