DQ sells 6 times as many orders of french fries as sonic everyday. If both sold 60 more orders DQ would only sell 3 times as many fries. How many do each sell before and after the incease?

Answer 1

S = number FF Sonic sells.
D = number FF DQ sells.
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D = 6S every day.
If each sells 60 more, then
D + 60 = 3(S + 60) or
D + 60 = 3S + 120 or
D = 3S + 120
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The two equators are as follows:
D = 6S
D = 3S + 120
Solve these two simultaneous equation for D and S (before the addition of 60), then add 60 to each to determine the number sold after adding 60 to each. Post your work if you get stuck.

Answer 2

Where did the 120 come from?