At a fruit market, John bought some oranges for a total of $20. Jenny visited another stall, and bought 10 more oranges for the same price. Given that the difference in price per orange
was 10 cents, how many oranges did John purchase?

40 oranges.

Step-by-step explanation:

We have the following information:

John bought "x" oranges for $ 20  plus each orange for John costs 20 / x.

After  Jenny bought x + 10 oranges for mimes $ 20  and also each orange for Jenny costs 20 / (x + 10) . They tell us that the difference in price was 10 cents, that is to say 0.10 dollars, we would have the following:

20 / x - 20 / (x + 10) = 0.10

solving:

20x + 200 - 20 * x = 0.10 (x² + 10 * x)

x² + 10 * x-2000 = 0

we factor

(x + 50) (x-40) = 0

x + 50 = 0 => x = -50, this answer cannot be

x - 40 = 0 => x = 40, it is a viable answer so John bought a total of 40 oranges.

hello from mrbilldoesmath!

answer:

the domain is the set { -2, 0, 2, 3}

discussion:

the domain is the set of x values in the ordered pairs (x,y). taking the x, or first component, of each ordered pair gives   -2, 0, 2, 3.

you,

mrb