Daca a + b = 20 si b + c = 30 ,calculati 3 . a + 7 . b + 4 . c ( dau coroana la cine ma ajuta )

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.

fist on the left goes with the third on the right. second on the left goes with the fourth on the right. third on the left goes with the second on the right. the fourth on the left goes with first on the right

0.02

step-by-step explanation:

time of 9 192 631 770 periods of the radiation corresponding to the transition between the 2 hyperfine levels of the ground state of the caesium 133 atom at 0 k (but other seconds are sometimes used in astronomy)