If a plumber is paid $7.70 per hour, what would she earn in a 35 hour week?

The rate of the earning of the plumber is $7.70. It is
asked to know the earning in a 35 hour week.

It is  just
multiplication of rate of earning per hour  * number of hours  worked that gives the
total earning for the number of hours worked.

Therefore the
plumber earns $7.70 * 35 = $269.5.

The multiplication is
done as follows:

7.70*35 = (7.70)30
+(7.5)*5

7.7*35 =
231.00+38.50

7.7*35 =
269.50.

Hope this helps.