Question

Collins is working.......

Answer 1

Let n represent the amount Colin earned on Sunday.

On Sat. he earned n/2; on Sun. he earned n; and on Friday he earned (1/2)(n/2).

Then n/2  +  n  + n/4 = $70

Mult. all terms by 4 to eliminate fractions:

2n + 4n + n = $280

7n = $280  =>  n = $40

Colin earned n/2, or $20, on Saturday; n, or $40, on Sunday; and n/4, or $10, on Friday.

Note that $20 and $40 and $10 add up to $70, as they must.