Answer
Jake's made a total sales of 600
Explanation:
Let Jake's pretzel = J
Let Lisa's sales = L
Jake's sells three times as many pretzels as Lisas
Mathematically,
J = 3L --------- equation 1
The difference between their sales is 400
That is: Jake's sales - Lisa's sales = 400
J - L = 400 --------- equation 2
Substitute equation 1 into 2
Since J = 3L
3L - L = 400
2L = 400
Divide both sides by 2
2L/2 = 400/2
L = 200
Hence, Lisa made 200 sales
Since Jake's sale = 3 * L
J = 3 * 200
J = 600 sales
Therefore, Jakes made a total sales of 600