Answer: 49-11x
This is the same as -11x+49
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Step-by-step explanation:
1 apple = x dollars
4 apples = 4x dollars, after multiplying both sides by 4
If Jessica buys 4 apples, then she spends 4x dollars.
Jessica has $19, so she'll have 19-4x dollars leftover after buying those four apples.
Similarly, Levi will have 30-7x dollars leftover when buying 7 apples for x dollars each.
Add up the leftover amounts to get...
(jessica's leftovers) + (Levi's leftovers)
(19-4x)+(30-7x)
19-4x+30-7x
(19+30)+(-4x-7x)
49-11x
This is the same as -11x+49 since you can think of 49-11x as 49+(-11x), and we can add two terms in any order we want.
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An alternative viewpoint
Pool up Jessica's and Levi's amount they start with to get 19+30 = 49 dollars
Jessica buys 4 apples and Levi buys 7 apples. In total, this is 4+7 = 11 apples. At x dollars an apple, they spend 11x dollars. So they'll have 49-11x dollars leftover after buying those 11 apples.