The answer is -9 c your welcome :)
If I understood correctly, the possibility of the man living 50 more years is 0.352, and the possibility of the woman living 50 more years is 0.5
We have to multiply both possibilities to get their union set, in this case, both being alive. In other words, we are going to consider the times both of these events are happening.
0.352 x 0.5 = 0.176
You need to know the length of two sides and the degree of one angle.
Sum up the running costs given for Jan, Feb, Mar and Apr.
Divide your result by 4 to find the average monthly running costs.
Mult. this average by 12 to estimate the annual running costs.