A. The shop charges $8.517 for a one-day rental
B. The shop charges $42.857 for a weekly rental.
Step-by-step explanation:
Step 1; The shop charges $x for a one-day rental and $5x for a weekly rental. Assume $x = a and $5x = b, from this we can write,
5a = b, take this as equation 1.
Step 2; The shop had a total sale of $600 by renting 20 boards for a one-day rental and 10 boards for a weekly rental. So,
20a + 10b = 600, take this as equation 2.
Substituting equation 1 in 2, we get
20a + 10 (5a) = 600,
20a + 50a = 600, a = 600 / 70,
a = $8.5714.
From equation 1, 5a = b,
5 × $8.5714 = b,
b = $42.857.
So for a one-day rental, the shop charges $8.5714 and for a weekly rental it charges $42.857.