Wolfgang and Heinrich worked as electricians at $14 and $12 respectively. One month Wolfgang worked 10 hours more than Heinrich. If their total income for the month was $3520, how many hours did each work during the month?

If x is the number of hours Heinrich works then his income would be 12x

If y is the number of hours Wolfgang works then his income would be 14y

If Wolfgang worked 10 hours more than Heinrich then:

y = x + 10

Now if their total income was $3520 then:

14 (x + 10) + 12x = 3520

14x + 140 + 12x = 3520

26x = 3380

x = 130, therefor Heinrich worked 130 hours

If x = 130:

y = 130 + 10 = 140, therefor Wolfgang worked 140 hours