It is given that
a+b=20 -------------------- (1)
b+c=30 -----------------------(2)
We have to calculate
3 a + 4 b +7 c
Now multiplying equation(1 )by 3,we get
3 a+ 3 b=60 ----------------------------------(3)
and Multiplying equation( 2) by 4,we get
4 b + 4 c=120 -----------------------------------(4)
Adding expression (3) and (4),we get i.e left hand side of 3 to left hand side of 4 and right hand side of 3 to right hand side of 4.
3 a+ 3 b+ 4 b+ 4 c=60+120
Adding like terms, we get
3 a+ 7 b+ 4 c =180, Which is the required solution.
I don’t remember how to do a and b but A is 39
I believe it’s 361, tell me if I’m wrong though!
Answers:
a. Given
b. Transitive property of congruence
c. Vertical angles are congruent
d. Transitive property of congruence
Let me know if you need any clarification as to how I got those answers. They should be self-explanatory but I'm happy to clarify further if needed.
