Answer
P(two or more children under the age of 18 and both spouses work) $=\frac{37}{170}\approx0.218$
Work Step by Step
The sample space: 1700 married couples. So, N(S) = 1700
According to the cell in the third row, third column: N(two or more children under the age of 18 and both spouses work) = 350.
P(two or more children under the age of 18 and both spouses work) =
$\frac{N(\text{two or more children under the age of 18 and both spouses work})}{N(S)}=\frac{370}{1700}=\frac{37}{170}\approx0.218.$
