I think you want the least common multipule (exg LCM of 2,3,4 is 12)
so we find the factors and include all of them so like this
15=3 times 5
12=2 times 2 times 3
8=2 times 2 times 2
so to include all of them we include 3 2's, 1 3 and 1 5 or 2 times 2 times 2 times 3 times 5 or 8 times 15 or 4 times 30 or 120
the LCM is 120
so 4/15=32/120
1/12=10/120
3/8=45/120
add 32/120+10/120+45/120=(32+10+45)/120=87/120
Answer:

Step-by-step explanation:
is an angle in the third quadrant
To find the reference angle subtract π from it
reference angle =
- π = 
To solve for P(QIR) we use the formula:
P(QIR)=[P(Q∩R)]/P(R)
But from the diagram:
P(Q∩R)=3/22
P(R)=7/22
hence
P(QIR)=3/22÷7/22=3/7
Simplify 6b2+7bc+2c2.
Hope this helps