Question

A bike and skate shop rents bike for $21 per day and pairs of skates for $20 per day. To remain viable, the shop needs to make at least $362 per day from bike and skate rentals combined. If they rent twice as many bikes as they do pairs of skates, what is the least number of pairs of skates they need to rent each day to make their minimum?

Answer 1

Let the number of bike be x and the number of skates be y, then
21x + 20y ≥ 362 . . . (1)
2y = x . . . (2)

Putting (2) into (1), then
21(2y) + 20y ≥ 362
42y + 20y ≥ 362
62y ≥ 362
y ≥ 5.84

The least number of pairs of skates they need to rent each day to make their minimum is 6.