Answer:
12 hours
Step-by-step explanation:
Given data
Steve= 4 hours
Steve and Andrea= 3 hours
Applying the combined work formula
1/A+1/B= 1/T
1/4+1/B= 1/3
solve for B
B+4/4B= 1/3
cross multiply
3(B+4)= 4B
3B+12= 4B
12= 4B-3B
12= B
Hence Andrea will spend 12 hours alone
c
0.25
we have
we know that
substitute
Remember that
so
0.65
5.16
6.5
6.51
31.56
you only put a parenthesis around a number if it is negative