Colin is working to earn some money for a CD player.On Saturday he earned half as much as he did on Sunday,but twice as much as he did on Friday.During those three days he earned $70.How much did he earn each day?

let Sat's earnings be x

Sunday = 2x
Friday = x/2

x + 2x + x/2 = 70
7x/2 = 70
x = 20

Friday: 10
Saturday: 20
Sunday: 40

To find out how much Colin earned each day, let's assume his earnings on Friday were x dollars.

According to the given information, on Saturday he earned half as much as he did on Sunday, which means his earnings on Sunday were 2x dollars.

Now, we know that his total earnings over the three days add up to $70. So, we can write the equation:

Friday's earnings + Saturday's earnings + Sunday's earnings = $70

x + (1/2)(2x) + 2x = 70

Simplifying the equation, we get:

x + x + 2x = 70

Combining like terms, we have:

4x = 70

To solve for x, we divide both sides of the equation by 4:

x = 70/4

x = 17.5

So, Colin earned $17.5 on Friday.

Now, let's find his earnings on Saturday and Sunday:

Saturday's earnings = (1/2)(2x) = (1/2)(2 * 17.5) = $17.5

Sunday's earnings = 2x = 2 * 17.5 = $35

Therefore, Colin earned $17.5 on Friday, $17.5 on Saturday, and $35 on Sunday.